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: <Z04uaWQxI3LXfAtg@google.com>
Date: Mon, 2 Dec 2024 14:02:17 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Zhongqiu Han <quic_zhonhan@...cinc.com>
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()

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


>  	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
>