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 <[email protected]> Signed-off-by: Andrey Ryabinin <[email protected]> --- 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
