Commit 8dc364fa authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
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libperf mmap: In user mmap rdpmc avoid undefined behavior 



A shift left of a signed 64-bit s64 may overflow and result in
undefined behavior caught by ubsan. Switch to a u64 instead.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent de1111f9

tools/lib/perf/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -508,7 +508,7 @@ int perf_mmap__read_self(struct perf_mmap *map, struct perf_counts_values *count 
		idx = READ_ONCE(pc->index);

		cnt = READ_ONCE(pc->offset);

		if (pc->cap_user_rdpmc && idx) {

			s64 evcnt = read_perf_counter(idx - 1);

			u64 evcnt = read_perf_counter(idx - 1);

			u16 width = READ_ONCE(pc->pmc_width);



			evcnt <<= 64 - width;