The comparison function cmp_profile_data() violates the C standard's requirements for qsort() comparison functions, which mandate symmetry and transitivity: * Symmetry: If x < y, then y > x. * Transitivity: If x < y and y < z, then x < z. When v1 and v2 are equal, the function incorrectly returns 1, breaking symmetry and transitivity. This causes undefined behavior, which can lead to memory corruption in certain versions of glibc [1]. Fix the issue by returning 0 when v1 and v2 are equal, ensuring compliance with the C standard and preventing undefined behavior. Link: https://www.qualys.com/2024/01/30/qsort.txt [1] Fixes: 0f223813edd0 ("perf ftrace: Add 'profile' command") Fixes: 74ae366c37b7 ("perf ftrace profile: Add -s/--sort option") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Kuan-Wei Chiu <visitorckw@xxxxxxxxx> --- tools/perf/builtin-ftrace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index 272d3c70810e..a56cf8b0a7d4 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -1151,8 +1151,9 @@ static int cmp_profile_data(const void *a, const void *b) if (v1 > v2) return -1; - else + if (v1 < v2) return 1; + return 0; } static void print_profile_result(struct perf_ftrace *ftrace) -- 2.34.1
