From: Rong Tao strnstr should not treat the ending '\0' of s2 as a matching character, otherwise the parameter 'len' will be meaningless, for example: 1. bpf_strnstr("openat", "open", 4) = -ENOENT 2. bpf_strnstr("openat", "open", 5) = 0 This patch makes (1) return 0, indicating a successful match. Signed-off-by: Rong Tao --- kernel/bpf/helpers.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 401b4932cc49..65bd0050c560 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3681,6 +3681,8 @@ __bpf_kfunc int bpf_strnstr(const char *s1__ign, const char *s2__ign, size_t len return -ENOENT; if (c1 != c2) break; + if (j == len - 1) + return i; } if (j == XATTR_SIZE_MAX) return -E2BIG; -- 2.51.0