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perf arm-spe: Reject zero nr_cpu in metadata to prevent division by zero

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arm_spe__alloc_metadata() reads nr_cpu from the auxtrace_info priv
array without validation.  When a crafted perf.data provides nr_cpu=0,
the per_cpu_sz calculation divides by zero:

  per_cpu_sz = (metadata_size - (hdr_sz * sizeof(u64))) / (*nr_cpu);

Reject nr_cpu <= 0 early, before the division.  The caller already
treats NULL return with metadata_ver != 1 as a parse failure.

Fixes: 7842a4b6ff ("perf arm-spe: Support metadata version 2")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Arnaldo Carvalho de Melo
2026-07-27 13:17:05 -03:00
committed by Namhyung Kim
parent b9fb822595
commit d67241d43b
1 changed files with 4 additions and 0 deletions
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4
tools/perf/util/arm-spe.c
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@@ -1605,6 +1605,10 @@ static u64 **arm_spe__alloc_metadata(struct perf_record_auxtrace_info *info,
hdr_sz = ptr[ARM_SPE_HEADER_SIZE];
*nr_cpu = ptr[ARM_SPE_CPUS_NUM];
/* nr_cpu is used as a divisor below */
if (*nr_cpu <= 0)
return NULL;
metadata = calloc(*nr_cpu, sizeof(*metadata));
if (!metadata)
return NULL;