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[34.121.155.132]) by smtp.gmail.com with ESMTPSA id 8926c6da1cb9f-4de049a491csm1661468173.155.2024.11.03.12.48.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 03 Nov 2024 12:48:38 -0800 (PST) From: Benjamin Peterson To: acme@kernel.org Cc: adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, benjamin@engflow.com, howardchu95@gmail.com, irogers@google.com, jolsa@kernel.org, kan.liang@linux.intel.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mark.rutland@arm.com, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org Subject: [PATCH v3] perf trace: avoid garbage when not printing a trace event's arguments Date: Sun, 3 Nov 2024 20:48:16 +0000 Message-Id: <20241103204816.7834-1-benjamin@engflow.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit trace__fprintf_tp_fields may not print any tracepoint arguments. E.g., if the argument values are all zero. Previously, this would result in a totally uninitialized buffer being passed to fprintf, which could lead to garbage on the console. Fix the problem by passing the number of initialized bytes fprintf. Fixes: f11b2803bb88 ("perf trace: Allow choosing how to augment the tracepoint arguments") Signed-off-by: Benjamin Peterson Tested-by: Howard Chu --- tools/perf/builtin-trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index d3f11b90d025..5af55f4192b5 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -3087,7 +3087,7 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct evsel *evsel, printed += syscall_arg_fmt__scnprintf_val(arg, bf + printed, size - printed, &syscall_arg, val); } - return printed + fprintf(trace->output, "%s", bf); + return printed + fprintf(trace->output, "%.*s", (int)printed, bf); } static int trace__event_handler(struct trace *trace, struct evsel *evsel, -- 2.39.5