netdev - Re: [PATCH] bpf: fix mem leak in error path of lwt bpf setup

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Message-ID: <20180521174352.oxhbjdghsdyi7dwe@kafai-mbp.dhcp.thefacebook.com>
Date:   Mon, 21 May 2018 10:44:08 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     Mathieu Xhonneux <m.xhonneux@...il.com>
CC:     <netdev@...r.kernel.org>, <daniel@...earbox.net>,
        <alexei.starovoitov@...il.com>
Subject: Re: [PATCH] bpf: fix mem leak in error path of lwt bpf setup

On Sun, May 20, 2018 at 02:08:57PM +0100, Mathieu Xhonneux wrote:
> In bpf_parse_prog, if bpf_prog_get_type fails, the function is
> immediately terminated without freeing the previously allocated
> prog->name.
> This patch adds a kfree before the return.
> 
> Signed-off-by: Mathieu Xhonneux <m.xhonneux@...il.com>
> ---
>  net/core/lwt_bpf.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
> index e7e626fb87bb..e142a7a32e46 100644
> --- a/net/core/lwt_bpf.c
> +++ b/net/core/lwt_bpf.c
> @@ -223,8 +223,10 @@ static int bpf_parse_prog(struct nlattr *attr, struct bpf_lwt_prog *prog,
>  
>  	fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
>  	p = bpf_prog_get_type(fd, type);
> -	if (IS_ERR(p))
> +	if (IS_ERR(p)) {
> +		kfree(prog->name);
I don't think it is needed.
The caller, "bpf_build_state()", does bpf_destroy_state() during error
out and it will eventually free up "name".

>  		return PTR_ERR(p);
> +	}
>  
>  	prog->prog = p;
>  
> -- 
> 2.16.1
>