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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net v2] ipv6: raw: fix use-after-free in rawv6_send_hdrinc() Message-ID: References: <20261026044808.613-1-n0ps1edzz@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Oct 27, 2026 at 10:43:48AM +0100, Antoine Tenart wrote: > On Tue, Oct 27, 2026 at 09:38:34AM +0800, Hangbin Liu wrote: > > On Mon, Oct 26, 2026 at 04:07:40PM +0100, Antoine Tenart wrote: > > > On Mon, Oct 26, 2026 at 02:09:23PM +0800, Hangbin Liu wrote: > > > > On Mon, Oct 26, 2026 at 12:48:08PM +0800, Zhou Qiuyue wrote: > > > > > diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c > > > > > index b965258cf..bdea82543 100644 > > > > > --- a/net/ipv6/raw.c > > > > > +++ b/net/ipv6/raw.c > > > > > @@ -654,6 +654,9 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length, > > > > > if (unlikely(!skb)) > > > > > return 0; > > > > > > > > > > + /* l3mdev_ip6_out() may have replaced the skb dst. */ > > > > > + rt = dst_rt6_info(skb_dst(skb)); > > > > > + > > > > > /* Acquire rcu_read_lock() in case we need to use rt->rt6i_idev > > > > > * in the error path. Since skb has been freed, the dst could > > > > > * have been queued for deletion. > > > > > > > > Reviewed-by: Hangbin Liu > > > > > > Doesn't this change the device seen by the nf hook / used for the stats? > > > > Should we still use the old/released rt->dst.dev after the VRF output > > path replace skb->dst? vrf_ip6_out_redirect() said it allows the nf hook > > use vrf device. > > Right, but then in the direct path the NF_INET_LOCAL_OUT hook would be > run twice with the same dev. Looking at other call sites for > l3mdev_ip6_out, it's not clear either, __ip6_local_out reloads the dev > while ip6_xmit does not. I'm not sure what is the expected behavior. Hmm, me neither. David might know. Thanks Hangbin > > Regardless of that, the change in behavior (if right) would be worth > mentioning in the commit log.