6.12-stable review patch. If anyone has any objections, please let me know.
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From: Kuan-Wei Chiu visitorckw@gmail.com
commit 246dfe3dc199246bd64635163115f2691623fc53 upstream.
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 visitorckw@gmail.com Reviewed-by: Namhyung Kim namhyung@kernel.org Reviewed-by: Arnaldo Carvalho de Melo acme@redhat.com 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 namhyung@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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)