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([140.113.216.168]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21644dcf724sm23863525ad.257.2024.12.09.05.42.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Dec 2024 05:42:33 -0800 (PST) From: Kuan-Wei Chiu To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org Cc: mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, kan.liang@linux.intel.com, adrian.hunter@intel.com, jserv@ccns.ncku.edu.tw, chuang@cs.nycu.edu.tw, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Kuan-Wei Chiu , stable@vger.kernel.org Subject: [PATCH] perf ftrace: Fix undefined behavior in cmp_profile_data() Date: Mon, 9 Dec 2024 21:42:26 +0800 Message-Id: <20241209134226.1939163-1-visitorckw@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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: Arnaldo Carvalho de Melo Reviewed-by: Namhyung Kim --- 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) =20 if (v1 > v2) return -1; - else + if (v1 < v2) return 1; + return 0; } =20 static void print_profile_result(struct perf_ftrace *ftrace) --=20 2.34.1