From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CBC3A47A0DD; Wed, 30 Sep 2026 18:09:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791762; cv=none; b=IFa9W6mb0/Dd/vom3y+zm3u4PuwGDdP9vAshiZN183eRblDxMmmi8raYNIVCvYH/o3oDyzLpXwiLQ+ZKCxs+7ZSz1oweAkruRYC2PsBh6/+/ru/zbKkMSoPCL/4j9fw91XtscEGH6+H17aVMGP43JQmjR+uDKyri8gU4flCvhX4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791762; c=relaxed/simple; bh=YysgYHOvVpuFWUqNcqd8Ezvd1xhAWJzxoKNM6pV1FFc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ss8ATLnRluxEWx/XHXqR4NtHk6Pp3q/scbqWXD7+rJdjT0sDJHkQJ0hj1WE2ZjqaSe7WZd8aHc8LF2FOckDq8d66gJRn+qIKT7+CqzLPwXNPlCOe8epMAIt5+Ts0Cp0vm1Qcd/TckCClMHJK/k6nMjbkvzg+Ryr/+apiVNqIaAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Bky34IBj; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Bky34IBj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 338161F000FF; Wed, 30 Sep 2026 18:09:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791760; bh=2SWL6w80na9wHgQxSOk5caRdX48Ua0ieESwE65Xfcb4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Bky34IBj32NkQ4T+A/sAjj3b9RVVYe36orpCQh/gnuKsLMPQCXdayFlfPNbtV9LPB 6dQ04f+i3+Ieu6HuTRf6E/vOuEoHQ64r2SDF7h1T36EhL8xaIR2lfzCt16rKyIzF4e 4Dv8mWghTiGPMUVVV3mrvKmZZqxVPL2tI8/9I9Fg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vega , Luxing Yin , Zihan Xi , Ido Schimmel , Jakub Kicinski Subject: [PATCH 5.15 371/752] ipv6: fix fib6 walker UAF on seq stop Date: Wed, 30 Sep 2026 17:24:01 +0200 Message-ID: <20260930152406.307117814@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zihan Xi commit 19b4ed644d68098cc62ab612727f40d30f43476c upstream. ipv6_route_iter_active() treats a walker in FWS_U at the table root as already unlinked. fib6_del_route() can move a still-linked walker into that same state when the current leaf is the last route at the root, so ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq private object can then be freed while it remains on net->ipv6.fib6_walkers. A later route deletion walks the dangling list and uses the freed walker. Use the list head as membership state and reinitialize it when unlinking. Keep the existing w->node check so a never-started iterator with a zeroed private object is not treated as linked. The same stop helper is used by /proc/net/ipv6_route and by the BPF ipv6_route iterator. The BPF show path only widens the race. Fixes: 8d2ca1d7b5c3 ("ipv6: avoid high order memory allocations for /proc/net/ipv6_route") Cc: stable@vger.kernel.org Reported-by: Vega Co-developed-by: Luxing Yin Signed-off-by: Luxing Yin Signed-off-by: Zihan Xi Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/89699735763f6c297584d7c2ff106239cc1e8ce0.1788837093.git.zihanx@nebusec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6_fib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -84,7 +84,7 @@ static void fib6_walker_link(struct net static void fib6_walker_unlink(struct net *net, struct fib6_walker *w) { write_lock_bh(&net->ipv6.fib6_walker_lock); - list_del(&w->lh); + list_del_init(&w->lh); write_unlock_bh(&net->ipv6.fib6_walker_lock); } @@ -2647,7 +2647,7 @@ static void *ipv6_route_seq_start(struct static bool ipv6_route_iter_active(struct ipv6_route_iter *iter) { struct fib6_walker *w = &iter->w; - return w->node && !(w->state == FWS_U && w->node == w->root); + return w->node && !list_empty(&w->lh); } static void ipv6_route_native_seq_stop(struct seq_file *seq, void *v)