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Date: Wed, 28 Feb 2024 23:07:57 -0800
Message-Id: <20240229070757.796244-1-irogers@google.com>
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Subject: [PATCH v1] libperf evlist: Avoid out-of-bounds access
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>, 
	Yang Jihong <yangjihong1@huawei.com>, linux-perf-users@vger.kernel.org, 
	linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

Parallel testing appears to show a race between allocating and setting
evsel ids. As there is a bounds check on the xyarray it yields a segv
like:

```
AddressSanitizer:DEADLYSIGNAL

=================================================================

==484408==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000010

==484408==The signal is caused by a WRITE memory access.

==484408==Hint: address points to the zero page.

    #0 0x55cef5d4eff4 in perf_evlist__id_hash tools/lib/perf/evlist.c:256
    #1 0x55cef5d4f132 in perf_evlist__id_add tools/lib/perf/evlist.c:274
    #2 0x55cef5d4f545 in perf_evlist__id_add_fd tools/lib/perf/evlist.c:315
    #3 0x55cef5a1923f in store_evsel_ids util/evsel.c:3130
    #4 0x55cef5a19400 in evsel__store_ids util/evsel.c:3147
    #5 0x55cef5888204 in __run_perf_stat tools/perf/builtin-stat.c:832
    #6 0x55cef5888c06 in run_perf_stat tools/perf/builtin-stat.c:960
    #7 0x55cef58932db in cmd_stat tools/perf/builtin-stat.c:2878
..
```

Avoid this crash by early exiting the perf_evlist__id_add_fd and
perf_evlist__id_add is the access is out-of-bounds.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/lib/perf/evlist.c                  | 18 ++++++++++++------
 tools/lib/perf/include/internal/evlist.h |  4 ++--
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index 058e3ff10f9b..c6d67fc9e57e 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -248,10 +248,10 @@ u64 perf_evlist__read_format(struct perf_evlist *evlist)
 
 static void perf_evlist__id_hash(struct perf_evlist *evlist,
 				 struct perf_evsel *evsel,
-				 int cpu, int thread, u64 id)
+				 int cpu_map_idx, int thread, u64 id)
 {
 	int hash;
-	struct perf_sample_id *sid = SID(evsel, cpu, thread);
+	struct perf_sample_id *sid = SID(evsel, cpu_map_idx, thread);
 
 	sid->id = id;
 	sid->evsel = evsel;
@@ -269,21 +269,27 @@ void perf_evlist__reset_id_hash(struct perf_evlist *evlist)
 
 void perf_evlist__id_add(struct perf_evlist *evlist,
 			 struct perf_evsel *evsel,
-			 int cpu, int thread, u64 id)
+			 int cpu_map_idx, int thread, u64 id)
 {
-	perf_evlist__id_hash(evlist, evsel, cpu, thread, id);
+	if (!SID(evsel, cpu_map_idx, thread))
+		return;
+
+	perf_evlist__id_hash(evlist, evsel, cpu_map_idx, thread, id);
 	evsel->id[evsel->ids++] = id;
 }
 
 int perf_evlist__id_add_fd(struct perf_evlist *evlist,
 			   struct perf_evsel *evsel,
-			   int cpu, int thread, int fd)
+			   int cpu_map_idx, int thread, int fd)
 {
 	u64 read_data[4] = { 0, };
 	int id_idx = 1; /* The first entry is the counter value */
 	u64 id;
 	int ret;
 
+	if (!SID(evsel, cpu_map_idx, thread))
+		return -1;
+
 	ret = ioctl(fd, PERF_EVENT_IOC_ID, &id);
 	if (!ret)
 		goto add;
@@ -312,7 +318,7 @@ int perf_evlist__id_add_fd(struct perf_evlist *evlist,
 	id = read_data[id_idx];
 
 add:
-	perf_evlist__id_add(evlist, evsel, cpu, thread, id);
+	perf_evlist__id_add(evlist, evsel, cpu_map_idx, thread, id);
 	return 0;
 }
 
diff --git a/tools/lib/perf/include/internal/evlist.h b/tools/lib/perf/include/internal/evlist.h
index d86ffe8ed483..f43bdb9b6227 100644
--- a/tools/lib/perf/include/internal/evlist.h
+++ b/tools/lib/perf/include/internal/evlist.h
@@ -126,11 +126,11 @@ u64 perf_evlist__read_format(struct perf_evlist *evlist);
 
 void perf_evlist__id_add(struct perf_evlist *evlist,
 			 struct perf_evsel *evsel,
-			 int cpu, int thread, u64 id);
+			 int cpu_map_idx, int thread, u64 id);
 
 int perf_evlist__id_add_fd(struct perf_evlist *evlist,
 			   struct perf_evsel *evsel,
-			   int cpu, int thread, int fd);
+			   int cpu_map_idx, int thread, int fd);
 
 void perf_evlist__reset_id_hash(struct perf_evlist *evlist);
 
-- 
2.44.0.278.ge034bb2e1d-goog