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2018-04-20proc: fix /proc/loadavg regressionAlexey Dobriyan1-1/+1
Commit 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API") changed last field of /proc/loadavg (last pid allocated) to be off by one: # unshare -p -f --mount-proc cat /proc/loadavg 0.00 0.00 0.00 1/60 2 <=== It should be 1 after first fork into pid namespace. This is formally a regression but given how useless this field is I don't think anyone is affected. Bug was found by /proc testsuite! Link: http://lkml.kernel.org/r/20180413175408.GA27246@avx2 Fixes: 95846ecf9dac508 ("pid: replace pid bitmap implementation with IDR API") Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Gargi Sharma <gs051095@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-20proc: revalidate kernel thread inodes to root:rootAlexey Dobriyan1-0/+6
task_dump_owner() has the following code: mm = task->mm; if (mm) { if (get_dumpable(mm) != SUID_DUMP_USER) { uid = ... } } Check for ->mm is buggy -- kernel thread might be borrowing mm and inode will go to some random uid:gid pair. Link: http://lkml.kernel.org/r/20180412220109.GA20978@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-20mm, pagemap: fix swap offset value for PMD migration entryHuang Ying1-1/+5
The swap offset reported by /proc/<pid>/pagemap may be not correct for PMD migration entries. If addr passed into pagemap_pmd_range() isn't aligned with PMD start address, the swap offset reported doesn't reflect this. And in the loop to report information of each sub-page, the swap offset isn't increased accordingly as that for PFN. This may happen after opening /proc/<pid>/pagemap and seeking to a page whose address doesn't align with a PMD start address. I have verified this with a simple test program. BTW: migration swap entries have PFN information, do we need to restrict whether to show them? [akpm@linux-foundation.org: fix typo, per Huang, Ying] Link: http://lkml.kernel.org/r/20180408033737.10897-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrei Vagin <avagin@openvz.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: "Jerome Glisse" <jglisse@redhat.com> Cc: Daniel Colascione <dancol@google.com> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-13proc: revalidate misc dentriesAlexey Dobriyan1-1/+22
If module removes proc directory while another process pins it by chdir'ing to it, then subsequent recreation of proc entry and all entries down the tree will not be visible to any process until pinning process unchdir from directory and unpins everything. Steps to reproduce: proc_mkdir("aaa", NULL); proc_create("aaa/bbb", ...); chdir("/proc/aaa"); remove_proc_entry("aaa/bbb", NULL); remove_proc_entry("aaa", NULL); proc_mkdir("aaa", NULL); # inaccessible because "aaa" dentry still points # to the original "aaa". proc_create("aaa/bbb", ...); Fix is to implement ->d_revalidate and ->d_delete. Link: http://lkml.kernel.org/r/20180312201938.GA4871@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11fs/proc/proc_sysctl.c: fix typo in sysctl_check_table_array()Waiman Long1-1/+1
Patch series "ipc: Clamp *mni to the real IPCMNI limit", v3. The sysctl parameters msgmni, shmmni and semmni have an inherent limit of IPC_MNI (32k). However, users may not be aware of that because they can write a value much higher than that without getting any error or notification. Reading the parameters back will show the newly written values which are not real. Enforcing the limit by failing sysctl parameter write, however, can break existing user applications. To address this delemma, a new flags field is introduced into the ctl_table. The value CTL_FLAGS_CLAMP_RANGE can be added to any ctl_table entries to enable a looser range clamping without returning any error. For example, .flags = CTL_FLAGS_CLAMP_RANGE, This flags value are now used for the range checking of shmmni, msgmni and semmni without breaking existing applications. If any out of range value is written to those sysctl parameters, the following warning will be printed instead. Kernel parameter "shmmni" was set out of range [0, 32768], clamped to 32768. Reading the values back will show 32768 instead of some fake values. This patch (of 6): Fix a typo. Link: http://lkml.kernel.org/r/1519926220-7453-2-git-send-email-longman@redhat.com Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: use slower rb_first()Alexey Dobriyan4-19/+17
In a typical for /proc "open+read+close" usecase, dentry is looked up successfully on open only to be killed in dput() on close. In fact dentries which aren't /proc/*/... and /proc/sys/* were almost NEVER CACHED. Simple printk in proc_lookup_de() shows that. Now that ->delete hook intelligently picks which dentries should live in dcache and which should not, rbtree caching is not necessary as dcache does it job, at last! As a side effect, struct proc_dir_entry shrinks by one pointer which can go into inline name. Link: http://lkml.kernel.org/r/20180314231032.GA15854@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: switch struct proc_dir_entry::count to refcountAlexey Dobriyan3-5/+6
->count is honest reference count unlike ->in_use. Link: http://lkml.kernel.org/r/20180313174550.GA4332@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: reject "." and ".." as filenamesAlexey Dobriyan1-0/+8
Various subsystems can create files and directories in /proc with names directly controlled by userspace. Which means "/", "." and ".." are no-no. "/" split is already taken care of, do the other 2 prohibited names. Link: http://lkml.kernel.org/r/20180310001223.GB12443@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Florian Westphal <fw@strlen.de> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: do mmput ASAP for /proc/*/map_filesAlexey Dobriyan1-1/+1
mm_struct is not needed while printing as all the data was already extracted. Link: http://lkml.kernel.org/r/20180309223120.GC3843@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: faster /proc/cmdlineAlexey Dobriyan1-1/+2
Use seq_puts() and skip format string processing. Link: http://lkml.kernel.org/r/20180309222948.GB3843@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: register filesystem lastAlexey Dobriyan1-6/+2
As soon as register_filesystem() exits, filesystem can be mounted. It is better to present fully operational /proc. Of course it doesn't matter because /proc is not modular but do it anyway. Drop error check, it should be handled by panicking. Link: http://lkml.kernel.org/r/20180309222709.GA3843@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: fix /proc/*/map_files lookup some moreAlexey Dobriyan1-0/+4
I totally forgot that _parse_integer() accepts arbitrary amount of leading zeroes leading to the following lookups: OK # readlink /proc/1/map_files/56427ecba000-56427eddc000 /lib/systemd/systemd bogus # readlink /proc/1/map_files/00000000000056427ecba000-56427eddc000 /lib/systemd/systemd # readlink /proc/1/map_files/56427ecba000-00000000000056427eddc000 /lib/systemd/systemd Link: http://lkml.kernel.org/r/20180303215130.GA23480@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: move "struct proc_dir_entry" into kmem cacheAlexey Dobriyan5-23/+52
"struct proc_dir_entry" is variable sized because of 0-length trailing array for name, however, because of SLAB padding allocations it is possible to make "struct proc_dir_entry" fixed sized and allocate same amount of memory. It buys fine-grained debugging with poisoning and usercopy protection which is not possible with kmalloc-* caches. Currently, on 32-bit 91+ byte allocations go into kmalloc-128 and on 64-bit 147+ byte allocations go to kmalloc-192 anyway. Additional memory is allocated only for 38/46+ byte long names which are rare or may not even exist in the wild. Link: http://lkml.kernel.org/r/20180223205504.GA17139@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11fs/proc/proc_sysctl.c: remove redundant link check in proc_sys_link_fill_cache()Danilo Krummrich1-6/+3
proc_sys_link_fill_cache() does not need to check whether we're called for a link - it's already done by scan(). Link: http://lkml.kernel.org/r/20180228013506.4915-2-danilokrummrich@dk-develop.de Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Luis R . Rodriguez" <mcgrof@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11fs/proc/proc_sysctl.c: fix potential page fault while unregistering sysctl tableDanilo Krummrich1-0/+3
proc_sys_link_fill_cache() does not take currently unregistering sysctl tables into account, which might result into a page fault in sysctl_follow_link() - add a check to fix it. This bug has been present since v3.4. Link: http://lkml.kernel.org/r/20180228013506.4915-1-danilokrummrich@dk-develop.de Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets") Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: "Luis R . Rodriguez" <mcgrof@kernel.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: use set_puts() at /proc/*/wchanAlexey Dobriyan1-1/+1
Link: http://lkml.kernel.org/r/20180217072011.GB16074@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: check permissions earlier for /proc/*/wchanAlexey Dobriyan1-5/+8
get_wchan() accesses stack page before permissions are checked, let's not play this game. Link: http://lkml.kernel.org/r/20180217071923.GA16074@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: replace seq_printf by seq_put_smth to speed up /proc/pid/statusAndrei Vagin1-5/+11
seq_printf() works slower than seq_puts, seq_puts, etc. == test_proc.c int main(int argc, char **argv) { int n, i, fd; char buf[16384]; n = atoi(argv[1]); for (i = 0; i < n; i++) { fd = open(argv[2], O_RDONLY); if (fd < 0) return 1; if (read(fd, buf, sizeof(buf)) <= 0) return 1; close(fd); } return 0; } == $ time ./test_proc 1000000 /proc/1/status == Before path == real 0m5.171s user 0m0.328s sys 0m4.783s == After patch == real 0m4.761s user 0m0.334s sys 0m4.366s Link: http://lkml.kernel.org/r/20180212074931.7227-4-avagin@openvz.org Signed-off-by: Andrei Vagin <avagin@openvz.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: replace seq_printf on seq_putc to speed up /proc/pid/smapsAndrei Vagin1-2/+3
seq_putc() works much faster than seq_printf() == Before patch == $ time python test_smaps.py real 0m3.828s user 0m0.413s sys 0m3.408s == After patch == $ time python test_smaps.py real 0m3.405s user 0m0.401s sys 0m3.003s == Before patch == - 75.51% 4.62% python [kernel.kallsyms] [k] show_smap.isra.33 - 70.88% show_smap.isra.33 + 24.82% seq_put_decimal_ull_aligned + 19.78% __walk_page_range + 12.74% seq_printf + 11.08% show_map_vma.isra.23 + 1.68% seq_puts == After patch == - 69.16% 5.70% python [kernel.kallsyms] [k] show_smap.isra.33 - 63.46% show_smap.isra.33 + 25.98% seq_put_decimal_ull_aligned + 20.90% __walk_page_range + 12.60% show_map_vma.isra.23 1.56% seq_putc + 1.55% seq_puts Link: http://lkml.kernel.org/r/20180212074931.7227-2-avagin@openvz.org Signed-off-by: Andrei Vagin <avagin@openvz.org> Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: add seq_put_decimal_ull_width to speed up /proc/pid/smapsAndrei Vagin2-89/+53
seq_put_decimal_ull_w(m, str, val, width) prints a decimal number with a specified minimal field width. It is equivalent of seq_printf(m, "%s%*d", str, width, val), but it works much faster. == test_smaps.py num = 0 with open("/proc/1/smaps") as f: for x in xrange(10000): data = f.read() f.seek(0, 0) == == Before patch == $ time python test_smaps.py real 0m4.593s user 0m0.398s sys 0m4.158s == After patch == $ time python test_smaps.py real 0m3.828s user 0m0.413s sys 0m3.408s $ perf -g record python test_smaps.py == Before patch == - 79.01% 3.36% python [kernel.kallsyms] [k] show_smap.isra.33 - 75.65% show_smap.isra.33 + 48.85% seq_printf + 15.75% __walk_page_range + 9.70% show_map_vma.isra.23 0.61% seq_puts == After patch == - 75.51% 4.62% python [kernel.kallsyms] [k] show_smap.isra.33 - 70.88% show_smap.isra.33 + 24.82% seq_put_decimal_ull_w + 19.78% __walk_page_range + 12.74% seq_printf + 11.08% show_map_vma.isra.23 + 1.68% seq_puts [akpm@linux-foundation.org: fix drivers/of/unittest.c build] Link: http://lkml.kernel.org/r/20180212074931.7227-1-avagin@openvz.org Signed-off-by: Andrei Vagin <avagin@openvz.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: account "struct pde_opener"Alexey Dobriyan1-1/+1
The allocation is persistent in fact as any fool can open a file in /proc and sit on it. Link: http://lkml.kernel.org/r/20180214082409.GC17157@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: move "struct pde_opener" to kmem cacheAlexey Dobriyan3-6/+10
"struct pde_opener" is fixed size and we can have more granular approach to debugging. For those who don't know, per cache SLUB poisoning and red zoning don't work if there is at least one object allocated which is hopeless in case of kmalloc-64 but not in case of standalone cache. Although systemd opens 2 files from the get go, so it is hopeless after all. Link: http://lkml.kernel.org/r/20180214082306.GB17157@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: randomize "struct pde_opener"Alexey Dobriyan1-1/+1
The more the merrier. Link: http://lkml.kernel.org/r/20180214081935.GA17157@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: faster open/close of files without ->release hookAlexey Dobriyan1-18/+23
The whole point of code in fs/proc/inode.c is to make sure ->release hook is called either at close() or at rmmod time. All if it is unnecessary if there is no ->release hook. Save allocation+list manipulations under spinlock in that case. Link: http://lkml.kernel.org/r/20180214063033.GA15579@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: move /proc/sysvipc creation to where it belongsAlexey Dobriyan1-4/+0
Move the proc_mkdir() call within the sysvipc subsystem such that we avoid polluting proc_root_init() with petty cpp. [dave@stgolabs.net: contributed changelog] Link: http://lkml.kernel.org/r/20180216161732.GA10297@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: do less stuff under ->pde_unload_lockAlexey Dobriyan1-5/+9
Commit ca469f35a8e9ef ("deal with races between remove_proc_entry() and proc_reg_release()") moved too much stuff under ->pde_unload_lock making a problem described at series "[PATCH v5] procfs: Improve Scaling in proc" worse. While RCU is being figured out, move kfree() out of ->pde_unload_lock. On my potato, difference is only 0.5% speedup with concurrent open+read+close of /proc/cmdline, but the effect should be more noticeable on more capable machines. $ perf stat -r 16 -- ./proc-j 16 Performance counter stats for './proc-j 16' (16 runs): 130569.502377 task-clock (msec) # 15.872 CPUs utilized ( +- 0.05% ) 19,169 context-switches # 0.147 K/sec ( +- 0.18% ) 15 cpu-migrations # 0.000 K/sec ( +- 3.27% ) 437 page-faults # 0.003 K/sec ( +- 1.25% ) 300,172,097,675 cycles # 2.299 GHz ( +- 0.05% ) 96,793,267,308 instructions # 0.32 insn per cycle ( +- 0.04% ) 22,798,342,298 branches # 174.607 M/sec ( +- 0.04% ) 111,764,687 branch-misses # 0.49% of all branches ( +- 0.47% ) 8.226574400 seconds time elapsed ( +- 0.05% ) ^^^^^^^^^^^ $ perf stat -r 16 -- ./proc-j 16 Performance counter stats for './proc-j 16' (16 runs): 129866.777392 task-clock (msec) # 15.869 CPUs utilized ( +- 0.04% ) 19,154 context-switches # 0.147 K/sec ( +- 0.66% ) 14 cpu-migrations # 0.000 K/sec ( +- 1.73% ) 431 page-faults # 0.003 K/sec ( +- 1.09% ) 298,556,520,546 cycles # 2.299 GHz ( +- 0.04% ) 96,525,366,833 instructions # 0.32 insn per cycle ( +- 0.04% ) 22,730,194,043 branches # 175.027 M/sec ( +- 0.04% ) 111,506,074 branch-misses # 0.49% of all branches ( +- 0.18% ) 8.183629778 seconds time elapsed ( +- 0.04% ) ^^^^^^^^^^^ Link: http://lkml.kernel.org/r/20180213132911.GA24298@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11proc: get rid of task lock/unlock pair to read umask for the "status" fileMateusz Guzik1-18/+5
get_task_umask locks/unlocks the task on its own. The only caller does the same thing immediately after. Utilize the fact the task has to be locked anyway and just do it once. Since there are no other users and the code is short, fold it in. Link: http://lkml.kernel.org/r/1517995608-23683-1-git-send-email-mguzik@redhat.com Signed-off-by: Mateusz Guzik <mguzik@redhat.com> Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11procfs: add seq_put_hex_ll to speed up /proc/pid/mapsAndrei Vagin1-9/+12
seq_put_hex_ll() prints a number in hexadecimal notation and works faster than seq_printf(). == test.py num = 0 with open("/proc/1/maps") as f: while num < 10000 : data = f.read() f.seek(0, 0) num = num + 1 == == Before patch == $ time python test.py real 0m1.561s user 0m0.257s sys 0m1.302s == After patch == $ time python test.py real 0m0.986s user 0m0.279s sys 0m0.707s $ perf -g record python test.py: == Before patch == - 67.42% 2.82% python [kernel.kallsyms] [k] show_map_vma.isra.22 - 64.60% show_map_vma.isra.22 - 44.98% seq_printf - seq_vprintf - vsnprintf + 14.85% number + 12.22% format_decode 5.56% memcpy_erms + 15.06% seq_path + 4.42% seq_pad + 2.45% __GI___libc_read == After patch == - 47.35% 3.38% python [kernel.kallsyms] [k] show_map_vma.isra.23 - 43.97% show_map_vma.isra.23 + 20.84% seq_path - 15.73% show_vma_header_prefix 10.55% seq_put_hex_ll + 2.65% seq_put_decimal_ull 0.95% seq_putc + 6.96% seq_pad + 2.94% __GI___libc_read [avagin@openvz.org: use unsigned int instead of int where it is suitable] Link: http://lkml.kernel.org/r/20180214025619.4005-1-avagin@openvz.org [avagin@openvz.org: v2] Link: http://lkml.kernel.org/r/20180117082050.25406-1-avagin@openvz.org Link: http://lkml.kernel.org/r/20180112185812.7710-1-avagin@openvz.org Signed-off-by: Andrei Vagin <avagin@openvz.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-03-16procfs: remove CONFIG_HARDWALL dependencyArnd Bergmann1-9/+0
Hardwall is a tile specific feature, and with the removal of the tile architecture, this has become dead code, so let's remove it. Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-02-14Merge branch 'x86-urgent-for-linus' of ↵Linus Torvalds1-0/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Ingo Molnar: "Misc fixes all across the map: - /proc/kcore vsyscall related fixes - LTO fix - build warning fix - CPU hotplug fix - Kconfig NR_CPUS cleanups - cpu_has() cleanups/robustification - .gitignore fix - memory-failure unmapping fix - UV platform fix" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm, mm/hwpoison: Don't unconditionally unmap kernel 1:1 pages x86/error_inject: Make just_return_func() globally visible x86/platform/UV: Fix GAM Range Table entries less than 1GB x86/build: Add arch/x86/tools/insn_decoder_test to .gitignore x86/smpboot: Fix uncore_pci_remove() indexing bug when hot-removing a physical CPU x86/mm/kcore: Add vsyscall page to /proc/kcore conditionally vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user page x86/Kconfig: Further simplify the NR_CPUS config x86/Kconfig: Simplify NR_CPUS config x86/MCE: Fix build warning introduced by "x86: do not use print_symbol()" x86/cpufeature: Update _static_cpu_has() to use all named variables x86/cpufeature: Reindent _static_cpu_has()
2018-02-13vfs/proc/kcore, x86/mm/kcore: Fix SMAP fault when dumping vsyscall user pageJia Zhang1-0/+4
Commit: df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data") ... introduced a bounce buffer to work around CONFIG_HARDENED_USERCOPY=y. However, accessing the vsyscall user page will cause an SMAP fault. Replace memcpy() with copy_from_user() to fix this bug works, but adding a common way to handle this sort of user page may be useful for future. Currently, only vsyscall page requires KCORE_USER. Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com> Reviewed-by: Jiri Olsa <jolsa@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jolsa@redhat.com Link: http://lkml.kernel.org/r/1518446694-21124-2-git-send-email-zhang.jia@linux.alibaba.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-11vfs: do bulk POLL* -> EPOLL* replacementLinus Torvalds2-3/+3
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script: for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done with de-mangling cleanups yet to come. NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al. The next patch from Al will sort out the final differences, and we should be all done. Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc/consoles.c: use seq_putc() in show_console_dev()Markus Elfring1-2/+1
A single character (line break) should be put into a sequence. Thus use the corresponding function "seq_putc". This issue was detected by using the Coccinelle software. Link: http://lkml.kernel.org/r/04fb69fe-d820-9141-820f-07e9a48f4635@users.sourceforge.net Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06proc: rearrange argsAlexey Dobriyan3-14/+13
Rearrange args for smaller code. lookup revolves around memcmp() which gets len 3rd arg, so propagate length as 3rd arg. readdir and lookup add additional arg to VFS ->readdir and ->lookup, so better add it to the end. Space savings on x86_64: add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-18 (-18) Function old new delta proc_readdir 22 13 -9 proc_lookup 18 9 -9 proc_match() is smaller if not inlined, I promise! Link: http://lkml.kernel.org/r/20180104175958.GB5204@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06proc: spread likely/unlikely a bitAlexey Dobriyan1-4/+4
use_pde() is used at every open/read/write/... of every random /proc file. Negative refcount happens only if PDE is being deleted by module (read: never). So it gets "likely". unuse_pde() gets "unlikely" for the same reason. close_pdeo() gets unlikely as the completion is filled only if there is a race between PDE removal and close() (read: never ever). It even saves code on x86_64 defconfig: add/remove: 0/0 grow/shrink: 1/2 up/down: 2/-20 (-18) Function old new delta close_pdeo 183 185 +2 proc_reg_get_unmapped_area 119 111 -8 proc_reg_poll 85 73 -12 Link: http://lkml.kernel.org/r/20180104175657.GA5204@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc: use __ro_after_initAlexey Dobriyan4-5/+9
/proc/self inode numbers, value of proc_inode_cache and st_nlink of /proc/$TGID are fixed constants. Link: http://lkml.kernel.org/r/20180103184707.GA31849@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc/internal.h: fix up commentAlexey Dobriyan1-1/+2
Document what ->pde_unload_lock actually does. Link: http://lkml.kernel.org/r/20180103185120.GB31849@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc/internal.h: rearrange struct proc_dir_entryAlexey Dobriyan1-10/+13
struct proc_dir_entry became bit messy over years: * move 16-bit ->mode_t before namelen to get rid of padding * make ->in_use first field: it seems to be most used resulting in smaller code on x86_64 (defconfig): add/remove: 0/0 grow/shrink: 7/13 up/down: 24/-67 (-43) Function old new delta proc_readdir_de 451 455 +4 proc_get_inode 282 286 +4 pde_put 65 69 +4 remove_proc_subtree 294 297 +3 remove_proc_entry 297 300 +3 proc_register 295 298 +3 proc_notify_change 94 97 +3 unuse_pde 27 26 -1 proc_reg_write 89 85 -4 proc_reg_unlocked_ioctl 85 81 -4 proc_reg_read 89 85 -4 proc_reg_llseek 87 83 -4 proc_reg_get_unmapped_area 123 119 -4 proc_entry_rundown 139 135 -4 proc_reg_poll 91 85 -6 proc_reg_mmap 79 73 -6 proc_get_link 55 49 -6 proc_reg_release 108 101 -7 proc_reg_open 298 291 -7 close_pdeo 228 218 -10 * move writeable fields together to a first cacheline (on x86_64), those include * ->in_use: reference count, taken every open/read/write/close etc * ->count: reference count, taken at readdir on every entry * ->pde_openers: tracks (nearly) every open, dirtied * ->pde_unload_lock: spinlock protecting ->pde_openers * ->proc_iops, ->proc_fops, ->data: writeonce fields, used right together with previous group. * other rarely written fields go into 1st/2nd and 2nd/3rd cacheline on 32-bit and 64-bit respectively. Additionally on 32-bit, ->subdir, ->subdir_node, ->namelen, ->name go fully into 2nd cacheline, separated from writeable fields. They are all used during lookup. Link: http://lkml.kernel.org/r/20171220215914.GA7877@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc/kcore.c: use probe_kernel_read() instead of memcpy()Heiko Carstens1-13/+5
Commit df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data") added a bounce buffer to avoid hardened usercopy checks. Copying to the bounce buffer was implemented with a simple memcpy() assuming that it is always valid to read from kernel memory iff the kern_addr_valid() check passed. A simple, but pointless, test case like "dd if=/proc/kcore of=/dev/null" now can easily crash the kernel, since the former execption handling on invalid kernel addresses now doesn't work anymore. Also adding a kern_addr_valid() implementation wouldn't help here. Most architectures simply return 1 here, while a couple implemented a page table walk to figure out if something is mapped at the address in question. With DEBUG_PAGEALLOC active mappings are established and removed all the time, so that relying on the result of kern_addr_valid() before executing the memcpy() also doesn't work. Therefore simply use probe_kernel_read() to copy to the bounce buffer. This also allows to simplify read_kcore(). At least on s390 this fixes the observed crashes and doesn't introduce warnings that were removed with df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data"), even though the generic probe_kernel_read() implementation uses uaccess functions. While looking into this I'm also wondering if kern_addr_valid() could be completely removed...(?) Link: http://lkml.kernel.org/r/20171202132739.99971-1-heiko.carstens@de.ibm.com Fixes: df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data") Fixes: f5509cc18daa ("mm: Hardened usercopy") Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Acked-by: Kees Cook <keescook@chromium.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc/array.c: delete children_seq_release()Alexey Dobriyan1-7/+1
It is 1:1 wrapper around seq_release(). Link: http://lkml.kernel.org/r/20171122171510.GA12161@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06proc: less memory for /proc/*/map_files readdirAlexey Dobriyan1-6/+9
dentry name can be evaluated later, right before calling into VFS. Also, spend less time under ->mmap_sem. Link: http://lkml.kernel.org/r/20171110163034.GA2534@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06fs/proc/vmcore.c: simpler /proc/vmcore cleanupAlexey Dobriyan1-4/+2
Iterators aren't necessary as you can just grab the first entry and delete it until no entries left. Link: http://lkml.kernel.org/r/20171121191121.GA20757@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06proc: fix /proc/*/map_files lookupAlexey Dobriyan1-1/+28
Current code does: if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2) However sscanf() is broken garbage. It silently accepts whitespace between format specifiers (did you know that?). It silently accepts valid strings which result in integer overflow. Do not use sscanf() for any even remotely reliable parsing code. OK # readlink '/proc/1/map_files/55a23af39000-55a23b05b000' /lib/systemd/systemd broken # readlink '/proc/1/map_files/ 55a23af39000-55a23b05b000' /lib/systemd/systemd broken # readlink '/proc/1/map_files/55a23af39000-55a23b05b000 ' /lib/systemd/systemd very broken # readlink '/proc/1/map_files/1000000000000000055a23af39000-55a23b05b000' /lib/systemd/systemd Andrei said: : This patch breaks criu. It was a bug in criu. And this bug is on a minor : path, which works when memfd_create() isn't available. It is a reason why : I ask to not backport this patch to stable kernels. : : In CRIU this bug can be triggered, only if this patch will be backported : to a kernel which version is lower than v3.16. Link: http://lkml.kernel.org/r/20171120212706.GA14325@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Andrei Vagin <avagin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06proc: don't use READ_ONCE/WRITE_ONCE for /proc/*/fail-nthAlexey Dobriyan1-3/+2
READ_ONCE and WRITE_ONCE are useless when there is only one read/write is being made. Link: http://lkml.kernel.org/r/20171120204033.GA9446@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06proc: use %u for pid printing and slightly less stackAlexey Dobriyan4-15/+14
PROC_NUMBUF is 13 which is enough for "negative int + \n + \0". However PIDs and TGIDs are never negative and newline is not a concern, so use just 10 per integer. Link: http://lkml.kernel.org/r/20171120203005.GA27743@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Alexander Viro <viro@ftp.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-01-31mm: use updated pmdp_invalidate() interface to track dirty/accessed bitsKirill A. Shutemov1-4/+4
Use the modifed pmdp_invalidate() that returns the previous value of pmd to transfer dirty and accessed bits. Link: http://lkml.kernel.org/r/20171213105756.69879-12-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Daney <david.daney@cavium.com> Cc: David Miller <davem@davemloft.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitin Gupta <nitin.m.gupta@oracle.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-01-31fs/proc/task_mmu.c: do not show VmExe bigger than total executable virtual ↵Konstantin Khlebnikov1-3/+8
memory If start_code / end_code pointers are screwed then "VmExe" could be bigger than total executable virtual memory and "VmLib" becomes negative: VmExe: 294320 kB VmLib: 18446744073709327564 kB VmExe and VmLib documented as text segment and shared library code size. Now their sum will be always equal to mm->exec_vm which sums size of executable and not writable and not stack areas. I've seen this for huge (>2Gb) statically linked binary which has whole world inside. For it start_code .. end_code range also covers one of rodata sections. Probably this is bug in customized linker, elf loader or both. Anyway CONFIG_CHECKPOINT_RESTORE allows to change these pointers, thus we cannot trust them without validation. Link: http://lkml.kernel.org/r/150728955451.743749.11276392315459539583.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-01-30Merge branch 'misc.poll' of ↵Linus Torvalds3-6/+6
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull poll annotations from Al Viro: "This introduces a __bitwise type for POLL### bitmap, and propagates the annotations through the tree. Most of that stuff is as simple as 'make ->poll() instances return __poll_t and do the same to local variables used to hold the future return value'. Some of the obvious brainos found in process are fixed (e.g. POLLIN misspelled as POLL_IN). At that point the amount of sparse warnings is low and most of them are for genuine bugs - e.g. ->poll() instance deciding to return -EINVAL instead of a bitmap. I hadn't touched those in this series - it's large enough as it is. Another problem it has caught was eventpoll() ABI mess; select.c and eventpoll.c assumed that corresponding POLL### and EPOLL### were equal. That's true for some, but not all of them - EPOLL### are arch-independent, but POLL### are not. The last commit in this series separates userland POLL### values from the (now arch-independent) kernel-side ones, converting between them in the few places where they are copied to/from userland. AFAICS, this is the least disruptive fix preserving poll(2) ABI and making epoll() work on all architectures. As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and it will trigger only on what would've triggered EPOLLWRBAND on other architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered at all on sparc. With this patch they should work consistently on all architectures" * 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits) make kernel-side POLL... arch-independent eventpoll: no need to mask the result of epi_item_poll() again eventpoll: constify struct epoll_event pointers debugging printk in sg_poll() uses %x to print POLL... bitmap annotate poll(2) guts 9p: untangle ->poll() mess ->si_band gets POLL... bitmap stored into a user-visible long field ring_buffer_poll_wait() return value used as return value of ->poll() the rest of drivers/*: annotate ->poll() instances media: annotate ->poll() instances fs: annotate ->poll() instances ipc, kernel, mm: annotate ->poll() instances net: annotate ->poll() instances apparmor: annotate ->poll() instances tomoyo: annotate ->poll() instances sound: annotate ->poll() instances acpi: annotate ->poll() instances crypto: annotate ->poll() instances block: annotate ->poll() instances x86: annotate ->poll() instances ...
2018-01-19proc: fix coredump vs read /proc/*/stat raceAlexey Dobriyan1-2/+5
do_task_stat() accesses IP and SP of a task without bumping reference count of a stack (which became an entity with independent lifetime at some point). Steps to reproduce: #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/time.h> #include <sys/resource.h> #include <unistd.h> #include <sys/wait.h> int main(void) { setrlimit(RLIMIT_CORE, &(struct rlimit){}); while (1) { char buf[64]; char buf2[4096]; pid_t pid; int fd; pid = fork(); if (pid == 0) { *(volatile int *)0 = 0; } snprintf(buf, sizeof(buf), "/proc/%u/stat", pid); fd = open(buf, O_RDONLY); read(fd, buf2, sizeof(buf2)); close(fd); waitpid(pid, NULL, 0); } return 0; } BUG: unable to handle kernel paging request at 0000000000003fd8 IP: do_task_stat+0x8b4/0xaf0 PGD 800000003d73e067 P4D 800000003d73e067 PUD 3d558067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 1417 Comm: a.out Not tainted 4.15.0-rc8-dirty #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc27 04/01/2014 RIP: 0010:do_task_stat+0x8b4/0xaf0 Call Trace: proc_single_show+0x43/0x70 seq_read+0xe6/0x3b0 __vfs_read+0x1e/0x120 vfs_read+0x84/0x110 SyS_read+0x3d/0xa0 entry_SYSCALL_64_fastpath+0x13/0x6c RIP: 0033:0x7f4d7928cba0 RSP: 002b:00007ffddb245158 EFLAGS: 00000246 Code: 03 b7 a0 01 00 00 4c 8b 4c 24 70 4c 8b 44 24 78 4c 89 74 24 18 e9 91 f9 ff ff f6 45 4d 02 0f 84 fd f7 ff ff 48 8b 45 40 48 89 ef <48> 8b 80 d8 3f 00 00 48 89 44 24 20 e8 9b 97 eb ff 48 89 44 24 RIP: do_task_stat+0x8b4/0xaf0 RSP: ffffc90000607cc8 CR2: 0000000000003fd8 John Ogness said: for my tests I added an else case to verify that the race is hit and correctly mitigated. Link: http://lkml.kernel.org/r/20180116175054.GA11513@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reported-by: "Kohli, Gaurav" <gkohli@codeaurora.org> Tested-by: John Ogness <john.ogness@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Oleg Nesterov <oleg@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-12-06proc: show si_ptr in /proc/<pid>/timers without hashingLinus Torvalds1-1/+1
It's a user pointer, and while the permissions of the file are pretty questionable (should it really be readable to everybody), hashing the pointer isn't going to be the solution. We should take a closer look at more of the /proc/<pid> file permissions in general. Sure, we do want many of them to often be readable (for 'ps' and friends), but I think we should probably do a few conversions from S_IRUGO to S_IRUSR. Reported-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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