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Subject[PATCH] perf evlist: fix memory corruption for Kernel PMU event
Date
Commit 7736627b865d ("perf stat: Use affinity for closing file
descriptors") will use FD(evsel, cpu, thread) to read and write
file descriptors xyarray. For a kernel PMU event, this leads to
serious memory corruption and perf crash.
I have seen evlist->core.cpus->nr is 1 while evsel has cpus->nr
with the total number of CPUs. so xyarray which is allocated by
evlist->core.cpus->nr will get overflow. This leads to various
segmentation faults in perf tool for kernel PMU events, eg:
./perf stat -e bus_cycles sleep 1
*** Error in `./perf': free(): invalid next size (fast): 0x00000000401e6370 ***
Aborted (core dumped)

Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors")
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
---
tools/perf/util/evlist.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index c0768c6..3022152 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1226,10 +1226,14 @@ void evlist__close(struct evlist *evlist)
int cpu, i;

/*
- * With perf record core.cpus is usually NULL.
+ * With perf record core.cpus is usually NULL;
+ * For Kernel PMU event x, "perf stat -e x" will set evlist->core.cpus->nr to
+ * 1 while evsel has cpus->nr which contains all CPUs. evsel__cpu_iter_skip()
+ * will be false, memory corruption will happen if we use affinity to close
+ * file descriptors;
* Use the old method to handle this for now.
*/
- if (!evlist->core.cpus) {
+ if (!evlist->core.cpus || evlist->core.cpus->nr == 1) {
evlist__for_each_entry_reverse(evlist, evsel)
evsel__close(evsel);
return;
--
2.7.4
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