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author | Andrey Ryabinin <aryabinin@virtuozzo.com> | 2018-02-01 21:00:50 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-31 08:28:44 +0300 |
commit | 9ce0c09dc2fd49e239c8a5f6b18f3bb3e72c0145 (patch) | |
tree | 078fd12d32766150dd182a2e90d4e61ffa011bf6 | |
parent | 8ac9e068f85abc5cf4ec52fffd162bfdd3c9c343 (diff) | |
download | linux-9ce0c09dc2fd49e239c8a5f6b18f3bb3e72c0145.tar.xz |
lib/strscpy: Shut up KASAN false-positives in strscpy()
[ Upstream commit 1a3241ff10d038ecd096d03380327f2a0b5840a6 ]
strscpy() performs the word-at-a-time optimistic reads. So it may may
access the memory past the end of the object, which is perfectly fine
since strscpy() doesn't use that (past-the-end) data and makes sure the
optimistic read won't cross a page boundary.
Use new read_word_at_a_time() to shut up the KASAN.
Note that this potentially could hide some bugs. In example bellow,
stscpy() will copy more than we should (1-3 extra uninitialized bytes):
char dst[8];
char *src;
src = kmalloc(5, GFP_KERNEL);
memset(src, 0xff, 5);
strscpy(dst, src, 8);
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | lib/string.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/string.c b/lib/string.c index 1530643edf00..33befc6ba3fa 100644 --- a/lib/string.c +++ b/lib/string.c @@ -203,7 +203,7 @@ ssize_t strscpy(char *dest, const char *src, size_t count) while (max >= sizeof(unsigned long)) { unsigned long c, data; - c = *(unsigned long *)(src+res); + c = read_word_at_a_time(src+res); if (has_zero(c, &data, &constants)) { data = prep_zero_mask(c, data, &constants); data = create_zero_mask(data); |