perf arm_spe: Handle missing CPU IDs

Don't call strtol() with a null pointer to avoid undefined behavior.

I'm not sure of the exact scenario for missing CPU IDs but I don't think
it happens in practice. SPE decoding can continue without them with
reduced functionality, but print an error message anyway.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 39046033e143..037c7aa150c1 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -982,16 +982,23 @@ static int arm_spe__get_midr(struct arm_spe *spe, int cpu, u64 *midr)
 
 		pr_warning_once("Old SPE metadata, re-record to improve decode accuracy\n");
 		cpuid = perf_env__cpuid(perf_session__env(spe->session));
+		if (!cpuid)
+			goto err;
+
 		*midr = strtol(cpuid, NULL, 16);
 		return 0;
 	}
 
 	metadata = arm_spe__get_metadata_by_cpu(spe, cpu);
 	if (!metadata)
-		return -EINVAL;
+		goto err;
 
 	*midr = metadata[ARM_SPE_CPU_MIDR];
 	return 0;
+
+err:
+	pr_warning_once("Failed to get MIDR for CPU %d\n", cpu);
+	return -EINVAL;
 }
 
 static void arm_spe__synth_ds(struct arm_spe_queue *speq,