From 0600597c854e53d2f9b7a6a718c1da2b8b4cb4db Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Fri, 31 May 2019 22:30:42 -0700 Subject: kasan: initialize tag to 0xff in __kasan_kmalloc 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 Link: http://lkml.kernel.org/r/20190502163057.6603-1-natechancellor@gmail.com Fixes: 7f94ffbc4c6a ("kasan: add hooks implementation for tag-based mode") Signed-off-by: Nathan Chancellor Reviewed-by: Andrey Konovalov Reviewed-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Nick Desaulniers Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/kasan/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm') 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(); -- cgit