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SubjectRe: [PATCH] IPv6/DCCP: Fix memory leak in dccp_v6_do_rcv()
On Fri, 29 Sep 2006 02:45:33 +0200
Jesper Juhl <jesper.juhl@gmail.com> wrote:

>
> Coverity found what looks like a real leak in net/dccp/ipv6.c::dccp_v6_do_rcv()
>
> We may leave via the return inside "if (sk->sk_state == DCCP_OPEN) {"
> but at that point we may have allocated opt_skb, but we never free it
> in that path before the return.
>
>
> Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
> ---
>
> net/dccp/ipv6.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> --- linux-2.6.18-git10-orig/net/dccp/ipv6.c 2006-09-28 22:40:07.000000000 +0200
> +++ linux-2.6.18-git10/net/dccp/ipv6.c 2006-09-29 02:35:15.000000000 +0200
> @@ -997,6 +997,8 @@ static int dccp_v6_do_rcv(struct sock *s
> if (sk->sk_state == DCCP_OPEN) { /* Fast path */
> if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
> goto reset;
> + if (opt_skb)
> + __kfree_skb(opt_skb);
> return 0;
> }

Looks right to me. But it'd be better coded as below, so we don't have
multiple deeply-nested return points (the cause of this bug) and duplicated
code.

otoh, it seems to me that opt_skb doesn't actually do anything and can be
removed?


diff -puN net/dccp/ipv6.c~ipv6-dccp-fix-memory-leak-in-dccp_v6_do_rcv net/dccp/ipv6.c
--- a/net/dccp/ipv6.c~ipv6-dccp-fix-memory-leak-in-dccp_v6_do_rcv
+++ a/net/dccp/ipv6.c
@@ -997,7 +997,7 @@ static int dccp_v6_do_rcv(struct sock *s
if (sk->sk_state == DCCP_OPEN) { /* Fast path */
if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
goto reset;
- return 0;
+ goto out;
}

if (sk->sk_state == DCCP_LISTEN) {
@@ -1013,9 +1013,7 @@ static int dccp_v6_do_rcv(struct sock *s
if (nsk != sk) {
if (dccp_child_process(sk, nsk, skb))
goto reset;
- if (opt_skb != NULL)
- __kfree_skb(opt_skb);
- return 0;
+ goto out;
}
}

@@ -1026,9 +1024,10 @@ static int dccp_v6_do_rcv(struct sock *s
reset:
dccp_v6_ctl_send_reset(skb);
discard:
+ kfree_skb(skb);
+out:
if (opt_skb != NULL)
__kfree_skb(opt_skb);
- kfree_skb(skb);
return 0;
}

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