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 0E6B24ABBB4; Thu, 17 Sep 2026 15:47:35 +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=1789660062; cv=none; b=avZp9zocLFSyUhgOIgLoC8DCUsaiNDBdxENKsBR//IHhO2+dMP4Ai+ZcOZBVAlb5J4muuzP7Bwnemwrj1I0YniMKQxizyyoSiZWnYtgG0fwtsGEoua9ofVxP8EAwtO9yBu4r0r9kCMHU6IqJM/j6CrM6yYbc1a+qmj/lOWstlY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789660062; c=relaxed/simple; bh=PZxIdAO/9RIbRz/uIIDFFb7/ztanSvdSXc5RdPmumTc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A289tRgfvCZ3GXB4+gDUniWTYY/MCZiRazdb5OJxP7AKGw8USUJaeI8QjE9K1k38h/A1XLE/YRF0b6MC4simpE/modlzOwYGpbsjfymtg0TQC+FOIdPKeulBAfiNb4EtmBNRA6xl3soQyNwyUghnVEjeqF2qFzTQO1a2Uk2A/WA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ORRkXXVr; 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="ORRkXXVr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEDE31F000FF; Thu, 17 Sep 2026 15:47:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789660053; bh=stt40wBsIMvlovm6kC6D5HGsZLnwZXlYU+iy+jkivDk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ORRkXXVryScOPZZJ0npL0H++GJD3eOUdqVtKQeEnkpGzFxA7YB9rMsCjEie5wM7b0 iQx7iVVbOAyJLQmw3vyiQ4/tDEqobVeTLl9khy0SHW//UxKw6BZehSiSVL0vxMCfY5 iY/VbVEq5iQkRgQwMXLNeh8XoTQEXguhRLTiIFAA= 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 7.2 464/733] ipv6: fix fib6 walker UAF on seq stop Date: Thu, 17 Sep 2026 16:12:52 +0100 Message-ID: <20260917151403.521950644@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151350.597953846@linuxfoundation.org> References: <20260917151350.597953846@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 7.2-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 @@ -85,7 +85,7 @@ 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); } @@ -2758,7 +2758,7 @@ 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)