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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-06 11:39:17 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-06 11:39:17 -0700 |
commit | 6ec62961e6de9506e8b8620dc19897d8cfd41c2e (patch) | |
tree | 8da8868e763b1fa1f5633acd549bc7e32eb0527e /mm | |
parent | 171c2bcbcb58a6699dad64d0c0b615af4f6ecb74 (diff) | |
parent | 29da93fea3ea39ab9b12270cc6be1b70ef201c9e (diff) | |
download | linux-6ec62961e6de9506e8b8620dc19897d8cfd41c2e.tar.bz2 |
Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool updates from Ingo Molnar:
"This is a series from Peter Zijlstra that adds x86 build-time uaccess
validation of SMAP to objtool, which will detect and warn about the
following uaccess API usage bugs and weirdnesses:
- call to %s() with UACCESS enabled
- return with UACCESS enabled
- return with UACCESS disabled from a UACCESS-safe function
- recursive UACCESS enable
- redundant UACCESS disable
- UACCESS-safe disables UACCESS
As it turns out not leaking uaccess permissions outside the intended
uaccess functionality is hard when the interfaces are complex and when
such bugs are mostly dormant.
As a bonus we now also check the DF flag. We had at least one
high-profile bug in that area in the early days of Linux, and the
checking is fairly simple. The checks performed and warnings emitted
are:
- call to %s() with DF set
- return with DF set
- return with modified stack frame
- recursive STD
- redundant CLD
It's all x86-only for now, but later on this can also be used for PAN
on ARM and objtool is fairly cross-platform in principle.
While all warnings emitted by this new checking facility that got
reported to us were fixed, there might be GCC version dependent
warnings that were not reported yet - which we'll address, should they
trigger.
The warnings are non-fatal build warnings"
* 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions
x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
sched/x86_64: Don't save flags on context switch
objtool: Add Direction Flag validation
objtool: Add UACCESS validation
objtool: Fix sibling call detection
objtool: Rewrite alt->skip_orig
objtool: Add --backtrace support
objtool: Rewrite add_ignores()
objtool: Handle function aliases
objtool: Set insn->func for alternatives
x86/uaccess, kcov: Disable stack protector
x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP
x86/uaccess, ubsan: Fix UBSAN vs. SMAP
x86/uaccess, kasan: Fix KASAN vs SMAP
x86/smap: Ditch __stringify()
x86/uaccess: Introduce user_access_{save,restore}()
x86/uaccess, signal: Fix AC=1 bloat
x86/uaccess: Always inline user_access_begin()
x86/uaccess, xen: Suppress SMAP warnings
...
Diffstat (limited to 'mm')
-rw-r--r-- | mm/kasan/Makefile | 3 | ||||
-rw-r--r-- | mm/kasan/common.c | 10 | ||||
-rw-r--r-- | mm/kasan/report.c | 3 |
3 files changed, 14 insertions, 2 deletions
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile index 5d1065efbd47..613dfe681e9f 100644 --- a/mm/kasan/Makefile +++ b/mm/kasan/Makefile @@ -2,11 +2,13 @@ KASAN_SANITIZE := n UBSAN_SANITIZE_common.o := n UBSAN_SANITIZE_generic.o := n +UBSAN_SANITIZE_generic_report.o := n UBSAN_SANITIZE_tags.o := n KCOV_INSTRUMENT := n CFLAGS_REMOVE_common.o = -pg CFLAGS_REMOVE_generic.o = -pg +CFLAGS_REMOVE_generic_report.o = -pg CFLAGS_REMOVE_tags.o = -pg # Function splitter causes unnecessary splits in __asan_load1/__asan_store1 @@ -14,6 +16,7 @@ CFLAGS_REMOVE_tags.o = -pg CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) +CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) obj-$(CONFIG_KASAN) := common.o init.o report.o diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 80bbe62b16cd..09c586474511 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -36,6 +36,7 @@ #include <linux/types.h> #include <linux/vmalloc.h> #include <linux/bug.h> +#include <linux/uaccess.h> #include "kasan.h" #include "../slab.h" @@ -614,6 +615,15 @@ void kasan_free_shadow(const struct vm_struct *vm) vfree(kasan_mem_to_shadow(vm->addr)); } +extern void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); + +void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) +{ + unsigned long flags = user_access_save(); + __kasan_report(addr, size, is_write, ip); + user_access_restore(flags); +} + #ifdef CONFIG_MEMORY_HOTPLUG static bool shadow_mapped(unsigned long addr) { diff --git a/mm/kasan/report.c b/mm/kasan/report.c index ca9418fe9232..0772820ad098 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -281,8 +281,7 @@ void kasan_report_invalid_free(void *object, unsigned long ip) end_report(&flags); } -void kasan_report(unsigned long addr, size_t size, - bool is_write, unsigned long ip) +void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) { struct kasan_access_info info; void *tagged_addr; |