linux-kernel - Re: [PATCH 3/3] perf bpf: Fix two memory leakages when calling perf_env__insert_bpf_prog

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Message-ID: <de297c20-8a91-48b5-96bd-e59019a780ef@quicinc.com>
Date: Tue, 3 Dec 2024 18:45:45 +0800
From: Zhongqiu Han <quic_zhonhan@...cinc.com>
To: Namhyung Kim <namhyung@...nel.org>
CC: <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...nel.org>, <irogers@...gle.com>, <adrian.hunter@...el.com>,
        <kan.liang@...ux.intel.com>, <james.clark@...aro.org>,
        <yangyicong@...ilicon.com>, <song@...nel.org>,
        <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <bpf@...r.kernel.org>
Subject: Re: [PATCH 3/3] perf bpf: Fix two memory leakages when calling
 perf_env__insert_bpf_prog_info()

On 12/3/2024 6:02 AM, Namhyung Kim wrote:
> Hello,
> 
> On Thu, Nov 28, 2024 at 08:54:32PM +0800, Zhongqiu Han wrote:
>> If perf_env__insert_bpf_prog_info() returns false due to a duplicate bpf
>> prog info node insertion, the temporary info_node and info_linear memory
>> will leak. Add a check to ensure the memory is freed if the function
>> returns false.
>>
>> Fixes: 9c51f8788b5d ("perf env: Avoid recursively taking env->bpf_progs.lock")
>> Signed-off-by: Zhongqiu Han <quic_zhonhan@...cinc.com>
>> ---
>>   tools/perf/util/bpf-event.c | 10 ++++++++--
>>   tools/perf/util/env.c       |  7 +++++--
>>   tools/perf/util/env.h       |  2 +-
>>   3 files changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
>> index 13608237c50e..c81444059ad0 100644
>> --- a/tools/perf/util/bpf-event.c
>> +++ b/tools/perf/util/bpf-event.c
>> @@ -289,7 +289,10 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
>>   		}
>>   
>>   		info_node->info_linear = info_linear;
>> -		perf_env__insert_bpf_prog_info(env, info_node);
>> +		if (!perf_env__insert_bpf_prog_info(env, info_node)) {
>> +			free(info_linear);
>> +			free(info_node);
>> +		}
>>   		info_linear = NULL;
>>   
>>   		/*
>> @@ -480,7 +483,10 @@ static void perf_env__add_bpf_info(struct perf_env *env, u32 id)
>>   	info_node = malloc(sizeof(struct bpf_prog_info_node));
>>   	if (info_node) {
>>   		info_node->info_linear = info_linear;
>> -		perf_env__insert_bpf_prog_info(env, info_node);
>> +		if (!perf_env__insert_bpf_prog_info(env, info_node)) {
>> +			free(info_linear);
>> +			free(info_node);
>> +		}
>>   	} else
>>   		free(info_linear);
>>   
>> diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
>> index d7865ae5f8f5..38401a289c24 100644
>> --- a/tools/perf/util/env.c
>> +++ b/tools/perf/util/env.c
>> @@ -24,12 +24,15 @@ struct perf_env perf_env;
>>   #include "bpf-utils.h"
>>   #include <bpf/libbpf.h>
>>   
>> -void perf_env__insert_bpf_prog_info(struct perf_env *env,
>> +bool perf_env__insert_bpf_prog_info(struct perf_env *env,
>>   				    struct bpf_prog_info_node *info_node)
>>   {
>> +	bool ret = true;
> 
> Please add a blank line between declaration and the other statements.
> Also I think you can just use the return value of the internal function
> instead of initializaing it to true.
> 
> Thanks,
> Namhyung
> 
> 

Hi Namhyung,
Thanks for your review~

I will add a blank line between the declaration and the other
statements, and optimize it as below:


+bool perf_env__insert_bpf_prog_info(struct perf_env *env,
  				    struct bpf_prog_info_node
*info_node)
  {
+	bool ret;
+
  	down_write(&env->bpf_progs.lock);
-	__perf_env__insert_bpf_prog_info(env, info_node);
+	ret = __perf_env__insert_bpf_prog_info(env, info_node);
  	up_write(&env->bpf_progs.lock);
+	return ret;
  }


>>   	down_write(&env->bpf_progs.lock);
>> -	__perf_env__insert_bpf_prog_info(env, info_node);
>> +	if (!__perf_env__insert_bpf_prog_info(env, info_node))
>> +		ret = false;
>>   	up_write(&env->bpf_progs.lock);
>> +	return ret;
>>   }
>>   
>>   bool __perf_env__insert_bpf_prog_info(struct perf_env *env, struct bpf_prog_info_node *info_node)
>> diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
>> index 9db2e5a625ed..da11add761d0 100644
>> --- a/tools/perf/util/env.h
>> +++ b/tools/perf/util/env.h
>> @@ -178,7 +178,7 @@ int perf_env__nr_cpus_avail(struct perf_env *env);
>>   void perf_env__init(struct perf_env *env);
>>   bool __perf_env__insert_bpf_prog_info(struct perf_env *env,
>>   				      struct bpf_prog_info_node *info_node);
>> -void perf_env__insert_bpf_prog_info(struct perf_env *env,
>> +bool perf_env__insert_bpf_prog_info(struct perf_env *env,
>>   				    struct bpf_prog_info_node *info_node);
>>   struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
>>   							__u32 prog_id);
>> -- 
>> 2.25.1
>>


-- 
Thx and BRs,
Zhongqiu Han