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| author | Peter Zijlstra <peterz@infradead.org> | 2019-04-03 10:39:50 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-04-03 12:02:24 +0300 |
| commit | 57b78a62e7f23c4686fe54091cdc3d12e60d6513 (patch) | |
| tree | d8ac655da75b7a72365c7226b93e78c06d0c9204 /mm/kasan/common.c | |
| parent | a936af8ea3580855adcc80daa8e01c0196afeb15 (diff) | |
| download | linux-57b78a62e7f23c4686fe54091cdc3d12e60d6513.tar.xz | |
x86/uaccess, kasan: Fix KASAN vs SMAP
KASAN inserts extra code for every LOAD/STORE emitted by te compiler.
Much of this code is simple and safe to run with AC=1, however the
kasan_report() function, called on error, is most certainly not safe
to call with AC=1.
Therefore wrap kasan_report() in user_access_{save,restore}; which for
x86 SMAP, saves/restores EFLAGS and clears AC before calling the real
function.
Also ensure all the functions are without __fentry__ hook. The
function tracer is also not safe.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/kasan/common.c')
| -rw-r--r-- | mm/kasan/common.c | 10 |
1 files changed, 10 insertions, 0 deletions
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) { |