linux-kernel - Re: [PATCH bpf-next 4/5] selftest/bpf: Fix memory leak in kprobe_multi

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Date:   Mon, 10 Oct 2022 11:01:23 +0200
From:   Jiri Olsa <olsajiri@...il.com>
To:     Xu Kuohai <xukuohai@...weicloud.com>
Cc:     bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, netdev@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Mykola Lysenko <mykolal@...com>,
        Shuah Khan <shuah@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Hou Tao <houtao1@...wei.com>,
        Dmitrii Dolgov <9erthalion6@...il.com>,
        Alan Maguire <alan.maguire@...cle.com>,
        Kui-Feng Lee <kuifeng@...com>,
        Kumar Kartikeya Dwivedi <memxor@...il.com>
Subject: Re: [PATCH bpf-next 4/5] selftest/bpf: Fix memory leak in
 kprobe_multi_test

On Sun, Oct 09, 2022 at 09:18:29AM -0400, Xu Kuohai wrote:
> From: Xu Kuohai <xukuohai@...wei.com>
> 
> The get_syms() function in kprobe_multi_test.c does not free the string
> memory allocated by sscanf correctly. Fix it.
> 
> Signed-off-by: Xu Kuohai <xukuohai@...wei.com>
> ---
>  .../bpf/prog_tests/kprobe_multi_test.c          | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> index d457a55ff408..07dd2c5b7f98 100644
> --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
> @@ -360,15 +360,14 @@ static int get_syms(char ***symsp, size_t *cntp)
>  		 * to them. Filter out the current culprits - arch_cpu_idle
>  		 * and rcu_* functions.
>  		 */
> -		if (!strcmp(name, "arch_cpu_idle"))
> -			continue;
> -		if (!strncmp(name, "rcu_", 4))
> -			continue;
> -		if (!strcmp(name, "bpf_dispatcher_xdp_func"))
> -			continue;
> -		if (!strncmp(name, "__ftrace_invalid_address__",
> -			     sizeof("__ftrace_invalid_address__") - 1))
> +		if (!strcmp(name, "arch_cpu_idle") ||
> +			!strncmp(name, "rcu_", 4) ||
> +			!strcmp(name, "bpf_dispatcher_xdp_func") ||
> +			!strncmp(name, "__ftrace_invalid_address__",
> +				 sizeof("__ftrace_invalid_address__") - 1)) {
> +			free(name);
>  			continue;
> +		}
>  		err = hashmap__add(map, name, NULL);
>  		if (err) {
>  			free(name);
> @@ -394,7 +393,7 @@ static int get_syms(char ***symsp, size_t *cntp)
>  	hashmap__free(map);
>  	if (err) {
>  		for (i = 0; i < cnt; i++)
> -			free(syms[cnt]);
> +			free(syms[i]);

mama mia.. nice catch! thanks

Acked-by: Jiri Olsa <jolsa@...nel.org>

jirka

>  		free(syms);
>  	}
>  	return err;
> -- 
> 2.25.1
>