Re: [PATCH] tools/lib/perf: Fix -Werror=alloc-size-larger-than in cpumap.c

[Venkat Rao Bagalkote <venkat88@linux.ibm.com>]

On 07/04/25 12:10 am, Athira Rajeev wrote:
>
>> On 6 Apr 2025, at 10:04 PM, Likhitha Korrapati <likhitha@linux.ibm.com> wrote:
>>
>> perf build break observed when using gcc 13-3 (FC39 ppc64le)
>> with the following error.
>>
>> cpumap.c: In function 'perf_cpu_map__merge':
>> cpumap.c:414:20: error: argument 1 range [18446744069414584320, 18446744073709551614] exceeds maximum object size 9223372036854775807 [-Werror=alloc-size-larger-than=]
>>   414 |         tmp_cpus = malloc(tmp_len * sizeof(struct perf_cpu));
>>       |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> In file included from cpumap.c:4:
>> /usr/include/stdlib.h:672:14: note: in a call to allocation function 'malloc' declared here
>>   672 | extern void *malloc (size_t __size) __THROW __attribute_malloc__
>>       |              ^~~~~~
>> cc1: all warnings being treated as errors
>>
>> Error happens to be only in gcc13-3 and not in latest gcc 14.
>> Even though git-bisect pointed bad commit as:
>> 'commit f5b07010c13c ("libperf: Don't remove -g when EXTRA_CFLAGS are used")',
>> issue is with tmp_len being "int". It holds number of cpus and making
>> it "unsigned int" fixes the issues.
>>
>> After the fix:
>>
>>   CC      util/pmu-flex.o
>>   CC      util/expr-flex.o
>>   LD      util/perf-util-in.o
>>   LD      perf-util-in.o
>>   AR      libperf-util.a
>>   LINK    perf
>>   GEN     python/perf.cpython-312-powerpc64le-linux-gnu.so
>>
>> Signed-off-by: Likhitha Korrapati <likhitha@linux.ibm.com>
> Looks good to me
>
> Reviewed-by: Athira Rajeev <atrajeev@linux.ibm.com>

Tested this patch on perf-tools-next repo, and this patch fixes the issue.

Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>


Regards,

Venkat.

>
> Thanks
> Athira
>> ---
>> tools/lib/perf/cpumap.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
>> index 4454a5987570..c7c784e18225 100644
>> --- a/tools/lib/perf/cpumap.c
>> +++ b/tools/lib/perf/cpumap.c
>> @@ -398,7 +398,7 @@ bool perf_cpu_map__is_subset(const struct perf_cpu_map *a, const struct perf_cpu
>> int perf_cpu_map__merge(struct perf_cpu_map **orig, struct perf_cpu_map *other)
>> {
>> struct perf_cpu *tmp_cpus;
>> - int tmp_len;
>> + unsigned int tmp_len;
>> int i, j, k;
>> struct perf_cpu_map *merged;
>>
>> -- 
>> 2.43.5
>>
>