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Date: Wed, 20 Mar 2024 09:26:19 -0700
Message-Id: <20240320162619.1272015-1-irogers@google.com>
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Mime-Version: 1.0
Subject: [PATCH v1] perf intel-pt: Fix memory sanitizer use-of-uninitialized-value
From: Ian Rogers <irogers@google.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, 
	Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung Kim <namhyung@kernel.org>, 
	Mark Rutland <mark.rutland@arm.com>, 
	Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>, 
	Ian Rogers <irogers@google.com>, Adrian Hunter <adrian.hunter@intel.com>, 
	Liam Howlett <liam.howlett@oracle.com>, Miguel Ojeda <ojeda@kernel.org>, 
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

Running the test "Miscellaneous Intel PT testing" with a build with
-fsanitize=memory and -fsanitize-memory-track-origins I saw:

```
==1257749==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5581c00a76b3 in intel_pt_sample_flags tools/perf/util/intel-pt.c:1527:17
    #1 0x5581c00c5cf6 in intel_pt_run_decoder tools/perf/util/intel-pt.c:2961:3
    #2 0x5581c00968f8 in intel_pt_process_timeless_queues tools/perf/util/intel-pt.c:3074:4
    #3 0x5581c007cf49 in intel_pt_process_event tools/perf/util/intel-pt.c:3482:10
    #4 0x5581bffa269a in auxtrace__process_event tools/perf/util/auxtrace.c:2830:9
    #5 0x5581bfb826c0 in perf_session__deliver_event tools/perf/util/session.c:1649:8
    #6 0x5581bfba1d7f in perf_session__process_event tools/perf/util/session.c:1891:9
    #7 0x5581bfba82e4 in process_simple tools/perf/util/session.c:2452:9
    #8 0x5581bfbabcc3 in reader__read_event tools/perf/util/session.c:2381:14
    #9 0x5581bfbad942 in reader__process_events tools/perf/util/session.c:2430:8
    #10 0x5581bfb78256 in __perf_session__process_events tools/perf/util/session.c:2477:8
    #11 0x5581bfb702c4 in perf_session__process_events tools/perf/util/session.c:2643:9
    #12 0x5581bf2da266 in __cmd_script tools/perf/builtin-script.c:2855:8
    #13 0x5581bf2bfcdd in cmd_script tools/perf/builtin-script.c:4402:8
    #14 0x5581bf67004b in run_builtin tools/perf/perf.c:350:11
    #15 0x5581bf66b8ea in handle_internal_command tools/perf/perf.c:403:8
    #16 0x5581bf66f527 in run_argv tools/perf/perf.c:447:2
    #17 0x5581bf669d2d in main tools/perf/perf.c:561:3

  Uninitialized value was stored to memory at
    #0 0x5581c005ddf8 in intel_pt_walk_insn tools/perf/util/intel-pt-decoder/intel-pt-decoder.c:1256:25
    #1 0x5581c001a932 in intel_pt_walk_fup tools/perf/util/intel-pt-decoder/intel-pt-decoder.c:1428:9
    #2 0x5581c000f76c in intel_pt_walk_trace tools/perf/util/intel-pt-decoder/intel-pt-decoder.c:3299:10
    #3 0x5581c000899b in intel_pt_decode tools/perf/util/intel-pt-decoder/intel-pt-decoder.c:3988:10
    #4 0x5581c00c5180 in intel_pt_run_decoder tools/perf/util/intel-pt.c:2941:11
    #5 0x5581c00968f8 in intel_pt_process_timeless_queues tools/perf/util/intel-pt.c:3074:4
    #6 0x5581c007cf49 in intel_pt_process_event tools/perf/util/intel-pt.c:3482:10
    #7 0x5581bffa269a in auxtrace__process_event tools/perf/util/auxtrace.c:2830:9
    #8 0x5581bfb826c0 in perf_session__deliver_event tools/perf/util/session.c:1649:8
    #9 0x5581bfba1d7f in perf_session__process_event tools/perf/util/session.c:1891:9
    #10 0x5581bfba82e4 in process_simple tools/perf/util/session.c:2452:9
    #11 0x5581bfbabcc3 in reader__read_event tools/perf/util/session.c:2381:14
    #12 0x5581bfbad942 in reader__process_events tools/perf/util/session.c:2430:8
    #13 0x5581bfb78256 in __perf_session__process_events tools/perf/util/session.c:2477:8
    #14 0x5581bfb702c4 in perf_session__process_events tools/perf/util/session.c:2643:9
    #15 0x5581bf2da266 in __cmd_script tools/perf/builtin-script.c:2855:8
    #16 0x5581bf2bfcdd in cmd_script tools/perf/builtin-script.c:4402:8
    #17 0x5581bf67004b in run_builtin tools/perf/perf.c:350:11
    #18 0x5581bf66b8ea in handle_internal_command tools/perf/perf.c:403:8
    #19 0x5581bf66f527 in run_argv tools/perf/perf.c:447:2
```

Adding a curly brace initializer for the intel_pt_insn in
intel_pt_walk_fup rectifies this, however, there may be other issues
lurking behind this so initialize all similar instances.

Fixes: f4aa081949e7 ("perf tools: Add Intel PT decoder")
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index b450178e3420..b4a95af2e4cc 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1115,7 +1115,7 @@ static void intel_pt_sample_insn(struct intel_pt_decoder *decoder)
  */
 static void intel_pt_sample_fup_insn(struct intel_pt_decoder *decoder)
 {
-	struct intel_pt_insn intel_pt_insn;
+	struct intel_pt_insn intel_pt_insn = {};
 	uint64_t max_insn_cnt, insn_cnt = 0;
 	int err;
 
@@ -1418,7 +1418,7 @@ static inline bool intel_pt_fup_with_nlip(struct intel_pt_decoder *decoder,
 
 static int intel_pt_walk_fup(struct intel_pt_decoder *decoder)
 {
-	struct intel_pt_insn intel_pt_insn;
+	struct intel_pt_insn intel_pt_insn = {};
 	uint64_t ip;
 	int err;
 
@@ -1461,7 +1461,7 @@ static int intel_pt_walk_fup(struct intel_pt_decoder *decoder)
 
 static int intel_pt_walk_tip(struct intel_pt_decoder *decoder)
 {
-	struct intel_pt_insn intel_pt_insn;
+	struct intel_pt_insn intel_pt_insn = {};
 	int err;
 
 	err = intel_pt_walk_insn(decoder, &intel_pt_insn, 0);
@@ -1626,7 +1626,7 @@ static int intel_pt_emulated_ptwrite(struct intel_pt_decoder *decoder)
 
 static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
 {
-	struct intel_pt_insn intel_pt_insn;
+	struct intel_pt_insn intel_pt_insn = {};
 	int err;
 
 	while (1) {
-- 
2.44.0.291.gc1ea87d7ee-goog