From: Kuan-Wei Chiu Date: Mon, 9 Dec 2024 13:42:26 +0000 (+0800) Subject: perf ftrace: Fix undefined behavior in cmp_profile_data() X-Git-Tag: v6.13-rc3~34^2~5 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=246dfe3dc199246bd64635163115f2691623fc53;p=thirdparty%2Flinux.git perf ftrace: Fix undefined behavior in cmp_profile_data() 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@vger.kernel.org Signed-off-by: Kuan-Wei Chiu Reviewed-by: Namhyung Kim Reviewed-by: Arnaldo Carvalho de Melo Cc: jserv@ccns.ncku.edu.tw Cc: chuang@cs.nycu.edu.tw Link: https://lore.kernel.org/r/20241209134226.1939163-1-visitorckw@gmail.com Signed-off-by: Namhyung Kim --- diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index 272d3c70810e7..a56cf8b0a7d40 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)