kasan: avoid -Wmaybe-uninitialized warning

gcc-7 produces this warning:

  mm/kasan/report.c: In function 'kasan_report':
  mm/kasan/report.c:351:3: error: 'info.first_bad_addr' may be used uninitialized in this function [-Werror=maybe-uninitialized]
     print_shadow_for_address(info->first_bad_addr);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  mm/kasan/report.c:360:27: note: 'info.first_bad_addr' was declared here

The code seems fine as we only print info.first_bad_addr when there is a
shadow, and we always initialize it in that case, but this is relatively
hard for gcc to figure out after the latest rework.

Adding an intialization to the most likely value together with the other
struct members shuts up that warning.

Fixes: b235b9808664 ("kasan: unify report headers")
Link: https://patchwork.kernel.org/patch/9641417/
Link: http://lkml.kernel.org/r/20170725152739.4176967-1-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Alexander Potapenko <glider@google.com>
Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 04bb1d3eb9ece0480182f2c738ed9d827fea3c62..6bcfb01ba0386e5bf2ec49512321e59a1fac0661 100644 (file)
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -401,6 +401,7 @@ void kasan_report(unsigned long addr, size_t size,
        disable_trace_on_warning();
 
        info.access_addr = (void *)addr;
+       info.first_bad_addr = (void *)addr;
        info.access_size = size;
        info.is_write = is_write;
        info.ip = ip;