6.6-stable review patch. If anyone has any objections, please let me know.
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From: Ian Rogers irogers@google.com
[ Upstream commit a0a4173631bfcfd3520192c0a61cf911d6a52c3a ]
Passing an empty map to perf_cpu_map__max triggered a SEGV. Explicitly test for the empty map.
Reported-by: Ingo Molnar mingo@kernel.org Closes: https://lore.kernel.org/linux-perf-users/aSwt7yzFjVJCEmVp@gmail.com/ Tested-by: Ingo Molnar mingo@kernel.org Signed-off-by: Ian Rogers irogers@google.com Tested-by: Thomas Richter tmricht@linux.ibm.com Signed-off-by: Namhyung Kim namhyung@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/lib/perf/cpumap.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c index 2a5a29217374..97f76d5457b9 100644 --- a/tools/lib/perf/cpumap.c +++ b/tools/lib/perf/cpumap.c @@ -367,10 +367,12 @@ struct perf_cpu perf_cpu_map__max(const struct perf_cpu_map *map) .cpu = -1 };
- // cpu_map__trim_new() qsort()s it, cpu_map__default_new() sorts it as well. - return __perf_cpu_map__nr(map) > 0 - ? __perf_cpu_map__cpu(map, __perf_cpu_map__nr(map) - 1) - : result; + if (!map) + return result; + + // The CPUs are always sorted and nr is always > 0 as 0 length map is + // encoded as NULL. + return __perf_cpu_map__cpu(map, __perf_cpu_map__nr(map) - 1); }
/** Is 'b' a subset of 'a'. */