Messages in this thread Patch in this message | | | From | Andrey Ryabinin <> | Subject | [PATCH] lib/strscpy: avoid KASAN false positive | Date | Tue, 18 Jul 2017 20:15:23 +0300 |
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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.
But KASAN doesn't know anything about that so it will complain. Let's just fallback to the byte-at-a-time reads under CONFIG_KASAN=y to avoid false-positives.
Reported-by: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> --- lib/string.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/lib/string.c b/lib/string.c index ebbb99c775bd..8b93d2519d5a 100644 --- a/lib/string.c +++ b/lib/string.c @@ -199,6 +199,13 @@ ssize_t strscpy(char *dest, const char *src, size_t count) max = 0; #endif + /* + * KASAN won't be happy about word-at-a-time + * optimistic reads, so let's avoid them. + */ + if (IS_ENABLED(CONFIG_KASAN)) + max = 0; + while (max >= sizeof(unsigned long)) { unsigned long c, data; -- 2.13.0
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