On 5/2/19 7:30 PM, Nathan Chancellor wrote: > When building with -Wuninitialized and CONFIG_KASAN_SW_TAGS unset, Clang > warns: > > mm/kasan/common.c:484:40: warning: variable 'tag' is uninitialized when > used here [-Wuninitialized] > kasan_unpoison_shadow(set_tag(object, tag), size); > ^~~ > > set_tag ignores tag in this configuration but clang doesn't realize it > at this point in its pipeline, as it points to arch_kasan_set_tag as > being the point where it is used, which will later be expanded to > (void *)(object) without a use of tag. Initialize tag to 0xff, as it > removes this warning and doesn't change the meaning of the code. > > Link: https://github.com/ClangBuiltLinux/linux/issues/465 > Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> Fixes: 7f94ffbc4c6a ("kasan: add hooks implementation for tag-based mode") Cc: <stable@xxxxxxxxxxxxxxx> Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > --- > > v1 -> v2: > > * Initialize tag to 0xff at Andrey's request > > mm/kasan/common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 36afcf64e016..242fdc01aaa9 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -464,7 +464,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, > { > unsigned long redzone_start; > unsigned long redzone_end; > - u8 tag; > + u8 tag = 0xff; > > if (gfpflags_allow_blocking(flags)) > quarantine_reduce(); >
