Messages in this thread | | | From | Dmitry Vyukov <> | Date | Thu, 23 Apr 2020 19:25:53 +0200 | Subject | Re: [PATCH v3 3/3] kasan: initialise array in kasan_memcmp test |
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On Thu, Apr 23, 2020 at 5:45 PM 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 939f395a5392..7700097842c8 100644 > --- a/lib/test_kasan.c > +++ b/lib/test_kasan.c > @@ -638,7 +638,7 @@ 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);
My version of this function contains the following below:
memset(arr, 0, sizeof(arr));
What am I missing?
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