From c47d7f56e914900410f65835933f9fc4374d0a2b Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Thu, 14 Dec 2017 15:32:24 -0800 Subject: include/linux/idr.h: add #include The was removed from radix-tree.h by commit f5bba9d11a25 ("include/linux/radix-tree.h: remove unneeded #include "). Since that commit, tools/testing/radix-tree/ couldn't pass compilation due to tools/testing/radix-tree/idr.c:17: undefined reference to WARN_ON_ONCE. This patch adds the bug.h header to idr.h to solve the issue. Link: http://lkml.kernel.org/r/1511963726-34070-2-git-send-email-wei.w.wang@intel.com Fixes: f5bba9d11a2 ("include/linux/radix-tree.h: remove unneeded #include ") Signed-off-by: Wei Wang Cc: Matthew Wilcox Cc: Jan Kara Cc: Eric Biggers Cc: Tejun Heo Cc: Masahiro Yamada Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/idr.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/idr.h b/include/linux/idr.h index 7c3a365f7e12..fa14f834e4ed 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -15,6 +15,7 @@ #include #include #include +#include struct idr { struct radix_tree_root idr_rt; -- cgit v1.2.3 From 338f1d9d1b829fec494d053f62820a2ee625b1ec Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 14 Dec 2017 15:32:28 -0800 Subject: lib/rbtree,drm/mm: add rbtree_replace_node_cached() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a variant of rbtree_replace_node() that maintains the leftmost cache of struct rbtree_root_cached when replacing nodes within the rbtree. As drm_mm is the only rb_replace_node() being used on an interval tree, the mistake looks fairly self-contained. Furthermore the only user of drm_mm_replace_node() is its testsuite... Testcase: igt/drm_mm/replace Link: http://lkml.kernel.org/r/20171122100729.3742-1-chris@chris-wilson.co.uk Link: https://patchwork.freedesktop.org/patch/msgid/20171109212435.9265-1-chris@chris-wilson.co.uk Fixes: f808c13fd373 ("lib/interval_tree: fast overlap detection") Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Acked-by: Davidlohr Bueso Cc: Jérôme Glisse Cc: Joonas Lahtinen Cc: Daniel Vetter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/gpu/drm/drm_mm.c | 8 +++++--- include/linux/rbtree.h | 2 ++ lib/rbtree.c | 10 ++++++++++ 3 files changed, 17 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index 61a1c8ea74bc..c3c79ee6119e 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -575,21 +575,23 @@ EXPORT_SYMBOL(drm_mm_remove_node); */ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new) { + struct drm_mm *mm = old->mm; + DRM_MM_BUG_ON(!old->allocated); *new = *old; list_replace(&old->node_list, &new->node_list); - rb_replace_node(&old->rb, &new->rb, &old->mm->interval_tree.rb_root); + rb_replace_node_cached(&old->rb, &new->rb, &mm->interval_tree); if (drm_mm_hole_follows(old)) { list_replace(&old->hole_stack, &new->hole_stack); rb_replace_node(&old->rb_hole_size, &new->rb_hole_size, - &old->mm->holes_size); + &mm->holes_size); rb_replace_node(&old->rb_hole_addr, &new->rb_hole_addr, - &old->mm->holes_addr); + &mm->holes_addr); } old->allocated = false; diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h index d574361943ea..fcbeed4053ef 100644 --- a/include/linux/rbtree.h +++ b/include/linux/rbtree.h @@ -99,6 +99,8 @@ extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, struct rb_root *root); extern void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, struct rb_root *root); +extern void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new, + struct rb_root_cached *root); static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, struct rb_node **rb_link) diff --git a/lib/rbtree.c b/lib/rbtree.c index ba4a9d165f1b..d3ff682fd4b8 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -603,6 +603,16 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new, } EXPORT_SYMBOL(rb_replace_node); +void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new, + struct rb_root_cached *root) +{ + rb_replace_node(victim, new, &root->rb_root); + + if (root->rb_leftmost == victim) + root->rb_leftmost = new; +} +EXPORT_SYMBOL(rb_replace_node_cached); + void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, struct rb_root *root) { -- cgit v1.2.3 From 146734b091430c80d80bb96b1139a96fb4bc830e Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 14 Dec 2017 15:32:34 -0800 Subject: string.h: workaround for increased stack usage The hardened strlen() function causes rather large stack usage in at least one file in the kernel, in particular when CONFIG_KASAN is enabled: drivers/media/usb/em28xx/em28xx-dvb.c: In function 'em28xx_dvb_init': drivers/media/usb/em28xx/em28xx-dvb.c:2062:1: error: the frame size of 3256 bytes is larger than 204 bytes [-Werror=frame-larger-than=] Analyzing this problem led to the discovery that gcc fails to merge the stack slots for the i2c_board_info[] structures after we strlcpy() into them, due to the 'noreturn' attribute on the source string length check. I reported this as a gcc bug, but it is unlikely to get fixed for gcc-8, since it is relatively easy to work around, and it gets triggered rarely. An earlier workaround I did added an empty inline assembly statement before the call to fortify_panic(), which works surprisingly well, but is really ugly and unintuitive. This is a new approach to the same problem, this time addressing it by not calling the 'extern __real_strnlen()' function for string constants where __builtin_strlen() is a compile-time constant and therefore known to be safe. We do this by checking if the last character in the string is a compile-time constant '\0'. If it is, we can assume that strlen() of the string is also constant. As a side-effect, this should also improve the object code output for any other call of strlen() on a string constant. [akpm@linux-foundation.org: add comment] Link: http://lkml.kernel.org/r/20171205215143.3085755-1-arnd@arndb.de Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 Link: https://patchwork.kernel.org/patch/9980413/ Link: https://patchwork.kernel.org/patch/9974047/ Fixes: 6974f0c4555 ("include/linux/string.h: add the option of fortified string.h functions") Signed-off-by: Arnd Bergmann Cc: Kees Cook Cc: Mauro Carvalho Chehab Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Daniel Micay Cc: Greg Kroah-Hartman Cc: Martin Wilck Cc: Dan Williams Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/string.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/string.h b/include/linux/string.h index 410ecf17de3c..cfd83eb2f926 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -259,7 +259,10 @@ __FORTIFY_INLINE __kernel_size_t strlen(const char *p) { __kernel_size_t ret; size_t p_size = __builtin_object_size(p, 0); - if (p_size == (size_t)-1) + + /* Work around gcc excess stack consumption issue */ + if (p_size == (size_t)-1 || + (__builtin_constant_p(p[p_size - 1]) && p[p_size - 1] == '\0')) return __builtin_strlen(p); ret = strnlen(p, p_size); if (p_size <= ret) -- cgit v1.2.3 From 3756f6401c302617c5e091081ca4d26ab604bec5 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 14 Dec 2017 15:32:41 -0800 Subject: exec: avoid gcc-8 warning for get_task_comm gcc-8 warns about using strncpy() with the source size as the limit: fs/exec.c:1223:32: error: argument to 'sizeof' in 'strncpy' call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess] This is indeed slightly suspicious, as it protects us from source arguments without NUL-termination, but does not guarantee that the destination is terminated. This keeps the strncpy() to ensure we have properly padded target buffer, but ensures that we use the correct length, by passing the actual length of the destination buffer as well as adding a build-time check to ensure it is exactly TASK_COMM_LEN. There are only 23 callsites which I all reviewed to ensure this is currently the case. We could get away with doing only the check or passing the right length, but it doesn't hurt to do both. Link: http://lkml.kernel.org/r/20171205151724.1764896-1-arnd@arndb.de Signed-off-by: Arnd Bergmann Suggested-by: Kees Cook Acked-by: Kees Cook Acked-by: Ingo Molnar Cc: Alexander Viro Cc: Peter Zijlstra Cc: Serge Hallyn Cc: James Morris Cc: Aleksa Sarai Cc: "Eric W. Biederman" Cc: Frederic Weisbecker Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/exec.c | 7 +++---- include/linux/sched.h | 6 +++++- 2 files changed, 8 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/fs/exec.c b/fs/exec.c index 6be2aa0ab26f..156f56acfe8e 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1216,15 +1216,14 @@ killed: return -EAGAIN; } -char *get_task_comm(char *buf, struct task_struct *tsk) +char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk) { - /* buf must be at least sizeof(tsk->comm) in size */ task_lock(tsk); - strncpy(buf, tsk->comm, sizeof(tsk->comm)); + strncpy(buf, tsk->comm, buf_size); task_unlock(tsk); return buf; } -EXPORT_SYMBOL_GPL(get_task_comm); +EXPORT_SYMBOL_GPL(__get_task_comm); /* * These functions flushes out all traces of the currently running executable diff --git a/include/linux/sched.h b/include/linux/sched.h index 21991d668d35..5124ba709830 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1503,7 +1503,11 @@ static inline void set_task_comm(struct task_struct *tsk, const char *from) __set_task_comm(tsk, from, false); } -extern char *get_task_comm(char *to, struct task_struct *tsk); +extern char *__get_task_comm(char *to, size_t len, struct task_struct *tsk); +#define get_task_comm(buf, tsk) ({ \ + BUILD_BUG_ON(sizeof(buf) != TASK_COMM_LEN); \ + __get_task_comm(buf, sizeof(buf), tsk); \ +}) #ifdef CONFIG_SMP void scheduler_ipi(void); -- cgit v1.2.3 From bdcf0a423ea1c40bbb40e7ee483b50fc8aa3d758 Mon Sep 17 00:00:00 2001 From: Thiago Rafael Becker Date: Thu, 14 Dec 2017 15:33:12 -0800 Subject: kernel: make groups_sort calling a responsibility group_info allocators In testing, we found that nfsd threads may call set_groups in parallel for the same entry cached in auth.unix.gid, racing in the call of groups_sort, corrupting the groups for that entry and leading to permission denials for the client. This patch: - Make groups_sort globally visible. - Move the call to groups_sort to the modifiers of group_info - Remove the call to groups_sort from set_groups Link: http://lkml.kernel.org/r/20171211151420.18655-1-thiago.becker@gmail.com Signed-off-by: Thiago Rafael Becker Reviewed-by: Matthew Wilcox Reviewed-by: NeilBrown Acked-by: "J. Bruce Fields" Cc: Al Viro Cc: Martin Schwidefsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/s390/kernel/compat_linux.c | 1 + fs/nfsd/auth.c | 3 +++ include/linux/cred.h | 1 + kernel/groups.c | 5 +++-- kernel/uid16.c | 1 + net/sunrpc/auth_gss/gss_rpc_xdr.c | 1 + net/sunrpc/auth_gss/svcauth_gss.c | 1 + net/sunrpc/svcauth_unix.c | 2 ++ 8 files changed, 13 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c index f04db3779b34..59eea9c65d3e 100644 --- a/arch/s390/kernel/compat_linux.c +++ b/arch/s390/kernel/compat_linux.c @@ -263,6 +263,7 @@ COMPAT_SYSCALL_DEFINE2(s390_setgroups16, int, gidsetsize, u16 __user *, grouplis return retval; } + groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info); diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c index 697f8ae7792d..f650e475d8f0 100644 --- a/fs/nfsd/auth.c +++ b/fs/nfsd/auth.c @@ -60,6 +60,9 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp) gi->gid[i] = exp->ex_anon_gid; else gi->gid[i] = rqgi->gid[i]; + + /* Each thread allocates its own gi, no race */ + groups_sort(gi); } } else { gi = get_group_info(rqgi); diff --git a/include/linux/cred.h b/include/linux/cred.h index 099058e1178b..631286535d0f 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -83,6 +83,7 @@ extern int set_current_groups(struct group_info *); extern void set_groups(struct cred *, struct group_info *); extern int groups_search(const struct group_info *, kgid_t); extern bool may_setgroups(void); +extern void groups_sort(struct group_info *); /* * The security context of a task diff --git a/kernel/groups.c b/kernel/groups.c index e357bc800111..daae2f2dc6d4 100644 --- a/kernel/groups.c +++ b/kernel/groups.c @@ -86,11 +86,12 @@ static int gid_cmp(const void *_a, const void *_b) return gid_gt(a, b) - gid_lt(a, b); } -static void groups_sort(struct group_info *group_info) +void groups_sort(struct group_info *group_info) { sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid), gid_cmp, NULL); } +EXPORT_SYMBOL(groups_sort); /* a simple bsearch */ int groups_search(const struct group_info *group_info, kgid_t grp) @@ -122,7 +123,6 @@ int groups_search(const struct group_info *group_info, kgid_t grp) void set_groups(struct cred *new, struct group_info *group_info) { put_group_info(new->group_info); - groups_sort(group_info); get_group_info(group_info); new->group_info = group_info; } @@ -206,6 +206,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) return retval; } + groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info); diff --git a/kernel/uid16.c b/kernel/uid16.c index ce74a4901d2b..ef1da2a5f9bd 100644 --- a/kernel/uid16.c +++ b/kernel/uid16.c @@ -192,6 +192,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t __user *, grouplist) return retval; } + groups_sort(group_info); retval = set_current_groups(group_info); put_group_info(group_info); diff --git a/net/sunrpc/auth_gss/gss_rpc_xdr.c b/net/sunrpc/auth_gss/gss_rpc_xdr.c index c4778cae58ef..444380f968f1 100644 --- a/net/sunrpc/auth_gss/gss_rpc_xdr.c +++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c @@ -231,6 +231,7 @@ static int gssx_dec_linux_creds(struct xdr_stream *xdr, goto out_free_groups; creds->cr_group_info->gid[i] = kgid; } + groups_sort(creds->cr_group_info); return 0; out_free_groups: diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 5dd4e6c9fef2..26531193fce4 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -481,6 +481,7 @@ static int rsc_parse(struct cache_detail *cd, goto out; rsci.cred.cr_group_info->gid[i] = kgid; } + groups_sort(rsci.cred.cr_group_info); /* mech name */ len = qword_get(&mesg, buf, mlen); diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c index 740b67d5a733..af7f28fb8102 100644 --- a/net/sunrpc/svcauth_unix.c +++ b/net/sunrpc/svcauth_unix.c @@ -520,6 +520,7 @@ static int unix_gid_parse(struct cache_detail *cd, ug.gi->gid[i] = kgid; } + groups_sort(ug.gi); ugp = unix_gid_lookup(cd, uid); if (ugp) { struct cache_head *ch; @@ -819,6 +820,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp) kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv)); cred->cr_group_info->gid[i] = kgid; } + groups_sort(cred->cr_group_info); if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) { *authp = rpc_autherr_badverf; return SVC_DENIED; -- cgit v1.2.3 From 4837fe37adff1d159904f0c013471b1ecbcb455e Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Thu, 14 Dec 2017 15:33:15 -0800 Subject: mm, oom_reaper: fix memory corruption David Rientjes has reported the following memory corruption while the oom reaper tries to unmap the victims address space BUG: Bad page map in process oom_reaper pte:6353826300000000 pmd:00000000 addr:00007f50cab1d000 vm_flags:08100073 anon_vma:ffff9eea335603f0 mapping: (null) index:7f50cab1d file: (null) fault: (null) mmap: (null) readpage: (null) CPU: 2 PID: 1001 Comm: oom_reaper Call Trace: unmap_page_range+0x1068/0x1130 __oom_reap_task_mm+0xd5/0x16b oom_reaper+0xff/0x14c kthread+0xc1/0xe0 Tetsuo Handa has noticed that the synchronization inside exit_mmap is insufficient. We only synchronize with the oom reaper if tsk_is_oom_victim which is not true if the final __mmput is called from a different context than the oom victim exit path. This can trivially happen from context of any task which has grabbed mm reference (e.g. to read /proc// file which requires mm etc.). The race would look like this oom_reaper oom_victim task mmget_not_zero do_exit mmput __oom_reap_task_mm mmput __mmput exit_mmap remove_vma unmap_page_range Fix this issue by providing a new mm_is_oom_victim() helper which operates on the mm struct rather than a task. Any context which operates on a remote mm struct should use this helper in place of tsk_is_oom_victim. The flag is set in mark_oom_victim and never cleared so it is stable in the exit_mmap path. Debugged by Tetsuo Handa. Link: http://lkml.kernel.org/r/20171210095130.17110-1-mhocko@kernel.org Fixes: 212925802454 ("mm: oom: let oom_reap_task and exit_mmap run concurrently") Signed-off-by: Michal Hocko Reported-by: David Rientjes Acked-by: David Rientjes Cc: Tetsuo Handa Cc: Andrea Argangeli Cc: [4.14] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/oom.h | 9 +++++++++ include/linux/sched/coredump.h | 1 + mm/mmap.c | 10 +++++----- mm/oom_kill.c | 4 +++- 4 files changed, 18 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/include/linux/oom.h b/include/linux/oom.h index 01c91d874a57..5bad038ac012 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -66,6 +66,15 @@ static inline bool tsk_is_oom_victim(struct task_struct * tsk) return tsk->signal->oom_mm; } +/* + * Use this helper if tsk->mm != mm and the victim mm needs a special + * handling. This is guaranteed to stay true after once set. + */ +static inline bool mm_is_oom_victim(struct mm_struct *mm) +{ + return test_bit(MMF_OOM_VICTIM, &mm->flags); +} + /* * Checks whether a page fault on the given mm is still reliable. * This is no longer true if the oom reaper started to reap the diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h index 9c8847395b5e..ec912d01126f 100644 --- a/include/linux/sched/coredump.h +++ b/include/linux/sched/coredump.h @@ -70,6 +70,7 @@ static inline int get_dumpable(struct mm_struct *mm) #define MMF_UNSTABLE 22 /* mm is unstable for copy_from_user */ #define MMF_HUGE_ZERO_PAGE 23 /* mm has ever used the global huge zero page */ #define MMF_DISABLE_THP 24 /* disable THP for all VMAs */ +#define MMF_OOM_VICTIM 25 /* mm is the oom victim */ #define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP) #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\ diff --git a/mm/mmap.c b/mm/mmap.c index a4d546821214..9efdc021ad22 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3019,20 +3019,20 @@ void exit_mmap(struct mm_struct *mm) /* Use -1 here to ensure all VMAs in the mm are unmapped */ unmap_vmas(&tlb, vma, 0, -1); - set_bit(MMF_OOM_SKIP, &mm->flags); - if (unlikely(tsk_is_oom_victim(current))) { + if (unlikely(mm_is_oom_victim(mm))) { /* * Wait for oom_reap_task() to stop working on this * mm. Because MMF_OOM_SKIP is already set before * calling down_read(), oom_reap_task() will not run * on this "mm" post up_write(). * - * tsk_is_oom_victim() cannot be set from under us - * either because current->mm is already set to NULL + * mm_is_oom_victim() cannot be set from under us + * either because victim->mm is already set to NULL * under task_lock before calling mmput and oom_mm is - * set not NULL by the OOM killer only if current->mm + * set not NULL by the OOM killer only if victim->mm * is found not NULL while holding the task_lock. */ + set_bit(MMF_OOM_SKIP, &mm->flags); down_write(&mm->mmap_sem); up_write(&mm->mmap_sem); } diff --git a/mm/oom_kill.c b/mm/oom_kill.c index c957be32b27a..29f855551efe 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -683,8 +683,10 @@ static void mark_oom_victim(struct task_struct *tsk) return; /* oom_mm is bound to the signal struct life time. */ - if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) + if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) { mmgrab(tsk->signal->oom_mm); + set_bit(MMF_OOM_VICTIM, &mm->flags); + } /* * Make sure that the task is woken up from uninterruptible sleep -- cgit v1.2.3