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lib/string: fix memchr_inv() for large ranges

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memchr_inv() takes a size_t length but counts 8 byte words in an unsigned
int.  At 32GiB that count wraps, so the scan can quietly miss most of the
range.

Use size_t for the word count.

Link: https://lore.kernel.org/20260621121133.16460-1-include@grrlz.net
Fixes: 798248206b ("lib/string.c: introduce memchr_inv()")
Signed-off-by: Bradley Morgan <include@grrlz.net>
Cc: Akinbou Mita <akinobu.mita@gmail.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Christoph Lameer <cl@linux-foundation.org>
Cc: Joern Engel <joern@logfs.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Bradley Morgan 2026-06-21 12:11:33 +00:00 committed by Andrew Morton
parent 2fdf181afd
commit c04cffb8c5
1 changed files with 2 additions and 1 deletions
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3
lib/string.c
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@ -821,7 +821,8 @@ void *memchr_inv(const void *start, int c, size_t bytes)
{
u8 value = c;
u64 value64;
unsigned int words, prefix;
size_t words;
unsigned int prefix;
if (bytes <= 16)
return check_bytes8(start, value, bytes);