| Message ID | 20200116062625.32692-4-dja@axtens.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix some incompatibilites between KASAN and FORTIFY_SOURCE | expand |
On Thu, Jan 16, 2020 at 7:26 AM Daniel Axtens <dja@axtens.net> wrote: > > memcmp may bail out before accessing all the memory if the buffers > contain differing bytes. kasan_memcmp calls memcmp with a stack array. > Stack variables are not necessarily initialised (in the absence of a > compiler plugin, at least). Sometimes this causes the memcpy to bail > early thus fail to trigger kasan. > > Make sure the array initialised to zero in the code. > > No other test is dependent on the contents of an array on the stack. > > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Signed-off-by: Daniel Axtens <dja@axtens.net> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> > --- > lib/test_kasan.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > index a130d75b9385..519b0f259e97 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -619,7 +619,7 @@ static noinline void __init kasan_memcmp(void) > { > char *ptr; > size_t size = 24; > - int arr[9]; > + int arr[9] = {}; > > pr_info("out-of-bounds in memcmp\n"); > ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO); > -- > 2.20.1 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20200116062625.32692-4-dja%40axtens.net.
diff --git a/lib/test_kasan.c b/lib/test_kasan.c index a130d75b9385..519b0f259e97 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -619,7 +619,7 @@ static noinline void __init kasan_memcmp(void) { char *ptr; size_t size = 24; - int arr[9]; + int arr[9] = {}; pr_info("out-of-bounds in memcmp\n"); ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
memcmp may bail out before accessing all the memory if the buffers contain differing bytes. kasan_memcmp calls memcmp with a stack array. Stack variables are not necessarily initialised (in the absence of a compiler plugin, at least). Sometimes this causes the memcpy to bail early thus fail to trigger kasan. Make sure the array initialised to zero in the code. No other test is dependent on the contents of an array on the stack. Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Daniel Axtens <dja@axtens.net> --- lib/test_kasan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)