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([2a0d:3344:5521:6b10:58fd:68f:7756:389d]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-495653c8760sm194729325e9.14.2026.07.23.02.58.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Jul 2026 02:58:06 -0700 (PDT) Message-ID: <265fc46b-1e33-4283-b94b-7c591a9cf3ba@redhat.com> Date: Thu, 23 Jul 2026 11:58:04 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net/x25: fix use-after-free in x25_kill_by_neigh() To: David Lee , Martin Schiller Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Simon Horman , Dominik 'Disconnect3d' Czarnota , linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260713104752.241175-1-david.lee@trailofbits.com> From: Paolo Abeni Content-Language: en-US In-Reply-To: <20260713104752.241175-1-david.lee@trailofbits.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/13/26 12:47 PM, David Lee wrote: > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c > index c31d2af5dd22..8aae9273b7c1 100644 > --- a/net/x25/af_x25.c > +++ b/net/x25/af_x25.c > @@ -1768,15 +1768,19 @@ void x25_kill_by_neigh(struct x25_neigh *nb) > { > struct sock *s; > > +again: > write_lock_bh(&x25_list_lock); > > sk_for_each(s, &x25_list) { > if (x25_sk(s)->neighbour == nb) { > + sock_hold(s); > write_unlock_bh(&x25_list_lock); > lock_sock(s); > - x25_disconnect(s, ENETUNREACH, 0, 0); > + if (x25_sk(s)->neighbour == nb) > + x25_disconnect(s, ENETUNREACH, 0, 0); > release_sock(s); > - write_lock_bh(&x25_list_lock); > + sock_put(s); > + goto again; > } > } > write_unlock_bh(&x25_list_lock); Note that sk will stay on list (with NULL neigh) even after disconnect and the above introduces a quadratic behavior, but I can't find an easy way to avoid it. /P