linux-kernel - Re: [PATCH v1 1/6] perf header: Replace hardcoded max cpus by MAX_NR

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <50e3ac65-fc5d-47d0-bdc4-5c8c1fc8eac1@amd.com>
Date: Wed, 28 Jan 2026 21:55:05 +0530
From: Swapnil Sapkal <swapnil.sapkal@....com>
To: Shrikanth Hegde <sshegde@...ux.ibm.com>, <acme@...nel.org>
CC: <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
	<jolsa@...nel.org>, <adrian.hunter@...el.com>, <thomas.falcon@...el.com>,
	<ashelat@...hat.com>, <yu.c.chen@...el.com>, <gautham.shenoy@....com>,
	<ravi.bangoria@....com>, <linux-kernel@...r.kernel.org>,
	<linux-perf-users@...r.kernel.org>, <peterz@...radead.org>,
	<mingo@...hat.com>, <namhyung@...nel.org>, <irogers@...gle.com>,
	<james.clark@....com>
Subject: Re: [PATCH v1 1/6] perf header: Replace hardcoded max cpus by
 MAX_NR_CPUS

Hi Srikanth, Arnaldo,

Thank you for reviewing the patches.

On 28-01-2026 13:09, Shrikanth Hegde wrote:
> 
> 
> On 1/28/26 12:19 AM, Swapnil Sapkal wrote:
>> cpumask and cpulist from cpu-domain header have hardcoded max_cpus value
>> of 1024. Current systems have more cpus than this value. Replace it with
>> MAX_NR_CPUS. Also define a macro to represent domain name length.
>>
>> Fixes: d40c68a49f69 ("perf header: Support CPU DOMAIN relation info")
>> Reported-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
>> Signed-off-by: Swapnil Sapkal <swapnil.sapkal@....com>
>> ---
>>   tools/perf/util/header.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
>> index eefd1cd73b6a..31c3bab1b10a 100644
>> --- a/tools/perf/util/header.c
>> +++ b/tools/perf/util/header.c
>> @@ -76,6 +76,7 @@ static const u64 __perf_magic2    = 
>> 0x32454c4946524550ULL;
>>   static const u64 __perf_magic2_sw = 0x50455246494c4532ULL;
>>   #define PERF_MAGIC    __perf_magic2
>> +#define DNAME_LEN    16
>>   const char perf_version_string[] = PERF_VERSION;
>> @@ -1616,10 +1617,10 @@ static int write_pmu_caps(struct feat_fd *ff,
>>   struct cpu_domain_map **build_cpu_domain_map(u32 *schedstat_version, 
>> u32 *max_sched_domains, u32 nr)
>>   {
>> +    char dname[DNAME_LEN], cpumask[MAX_NR_CPUS];
>>       struct domain_info *domain_info;
>>       struct cpu_domain_map **cd_map;
>> -    char dname[16], cpumask[256];
>> -    char cpulist[1024];
>> +    char cpulist[MAX_NR_CPUS];
>>       char *line = NULL;
>>       u32 cpu, domain;
>>       u32 dcount = 0;
> 
> Looking at
> https://lore.kernel.org/all/20260119175833.340369-3-swapnil.sapkal@amd.com/
> 
> There was one more "char cpus[1024]"  in tools/perf/util/util.c.
> You may need to fix that too. It is unlikely but, if one has created 
> exclusive
> cpusets comprising of only one cpu from a core, maybe you will run out 
> the length.
> So better use the MAX_NR_CPUS there as well.

Yes, I missed this.

Arnaldo, can you please consider the below diff? Let me know if you'd 
like me to respin the patch.

--
Thanks and Regards,
Swapnil

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index c83e59e8c787..3795d5182ce8 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -262,7 +262,7 @@ void cpumask_to_cpulist(char *cpumask, char *cpulist)
         int i, j, bm_size, nbits;
         int len = strlen(cpumask);
         unsigned long *bm;
-       char cpus[1024];
+       char cpus[MAX_NR_CPUS];

         for (i = 0; i < len; i++) {
                 if (cpumask[i] == ',') {
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 394dbfa944ac..c43f17137efd 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -6,6 +6,7 @@
  /* glibc 2.20 deprecates _BSD_SOURCE in favour of _DEFAULT_SOURCE */
  #define _DEFAULT_SOURCE 1

+#include "perf.h"
  #include <dirent.h>
  #include <fcntl.h>
  #include <stdbool.h>