[PATCH 6.9 067/374] perf intel-pt: Fix unassigned instruction op (discovered by MemorySanitizer)

Greg Kroah-Hartman
2024-06-06T14:08:44Z

From: Adrian Hunter <adrian.hunter@intel.com>

[ Upstream commit e101a05f79fd4ee3e89d2f3fb716493c33a33708 ]

MemorySanitizer discovered instances where the instruction op value was
not assigned.:

WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x5581c00a76b3 in intel_pt_sample_flags tools/perf/util/intel-pt.c:1527:17
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

The op value is used to set branch flags for branch instructions
encountered when walking the code, so fix by setting op to
INTEL_PT_OP_OTHER in other cases.

Fixes: 4c761d805bb2d2ea ("perf intel-pt: Fix intel_pt_fup_event() assumptions about setting state type")
Reported-by: Ian Rogers <irogers@google.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Closes: https://lore.kernel.org/linux-perf-users/20240320162619.1272015-1-irogers@google.com/
Link: https://lore.kernel.org/r/20240326083223.10883-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 2 ++
tools/perf/util/intel-pt.c | 2 ++
2 files changed, 4 insertions(+)

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 b450178e3420b..e733f6b1f7ac5 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1319,6 +1319,8 @@ static bool intel_pt_fup_event(struct intel_pt_decoder *decoder, bool no_tip)
bool ret = false;

decoder->state.type &= ~INTEL_PT_BRANCH;
+ decoder->state.insn_op = INTEL_PT_OP_OTHER;
+ decoder->state.insn_len = 0;

if (decoder->set_fup_cfe_ip || decoder->set_fup_cfe) {
bool ip = decoder->set_fup_cfe_ip;
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index f38893e0b0369..4db9a098f5926 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -764,6 +764,7 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,

addr_location__init(&al);
intel_pt_insn->length = 0;
+ intel_pt_insn->op = INTEL_PT_OP_OTHER;

if (to_ip && *ip == to_ip)
goto out_no_cache;
@@ -898,6 +899,7 @@ static int intel_pt_walk_next_insn(struct intel_pt_insn *intel_pt_insn,

if (to_ip && *ip == to_ip) {
intel_pt_insn->length = 0;
+ intel_pt_insn->op = INTEL_PT_OP_OTHER;
goto out_no_cache;
}

--
2.43.0