From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 EDEAD2D2491; Thu, 12 Mar 2026 20:25:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773347153; cv=none; b=ATkwviq/wrOMRGGSvU6CXXMn/76Nicvl6AsRvp2hd/YLBQtX+JokLH2WjhX3fCQG2Kid3130svDN8+QClaxxtVjNRTjOUBKQAV8i+A27MIDbT0jb3Alm02gpoKSHb76ricXufaxGK0TOB0QhBVhynbBAAqI+aSNJgfgBJOaSO3s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773347153; c=relaxed/simple; bh=rR61WDTTHNF7HjDfVfY95g4wc/Wswn7u0c7IzTQA1wk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=E1EoCHUaO2lzSMRqTmYYpkrxFSr7sVVk7jfWLXOgytLUNcE7tgqJ+bAT7zEIoVHHTB5zH/O8DB/XwzioRrySkRVc54To7ojHGQ1Bj7A7F5ge2xFm2W0vDH39nTxu4XBtQvmmCBUlwLKi5GIPgSzKIsCI9ZCwtYwBOAgGa6QNHuw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0sAb6BMT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0sAb6BMT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73F4BC4CEF7; Thu, 12 Mar 2026 20:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773347152; bh=rR61WDTTHNF7HjDfVfY95g4wc/Wswn7u0c7IzTQA1wk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0sAb6BMTcGb2JWmofvqBahLwy/lW2lY278Ei8wxjW3hbOWlfC/vIMuXfqyQweqtOf Ci206CF2SH4DW1bBY1NnHG/5VZSwEd+JoPfzadsn+9zSIBOwnOtaAM6Fik9Vf/DbSk DGEewHPzKU8w9zlPJh7ktysMKq8zmtE1zyInPexM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Ahern , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 217/265] ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu() Date: Thu, 12 Mar 2026 21:10:04 +0100 Message-ID: <20260312201026.160168000@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260312201018.128816016@linuxfoundation.org> References: <20260312201018.128816016@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jakub Kicinski [ Upstream commit 2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a ] l3mdev_master_dev_rcu() can return NULL when the slave device is being un-slaved from a VRF. All other callers deal with this, but we lost the fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu() with commit 4832c30d5458 ("net: ipv6: put host and anycast routes on device with address"). KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418) Call Trace: ip6_pol_route (net/ipv6/route.c:2318) fib6_rule_lookup (net/ipv6/fib6_rules.c:115) ip6_route_output_flags (net/ipv6/route.c:2607) vrf_process_v6_outbound (drivers/net/vrf.c:437) I was tempted to rework the un-slaving code to clear the flag first and insert synchronize_rcu() before we remove the upper. But looks like the explicit fallback to loopback_dev is an established pattern. And I guess avoiding the synchronize_rcu() is nice, too. Fixes: 4832c30d5458 ("net: ipv6: put host and anycast routes on device with address") Reviewed-by: David Ahern Link: https://patch.msgid.link/20260301194548.927324-1-kuba@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv6/route.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index aeac45af3a22a..0f741aa154faf 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1064,7 +1064,8 @@ static struct net_device *ip6_rt_get_dev_rcu(const struct fib6_result *res) */ if (netif_is_l3_slave(dev) && !rt6_need_strict(&res->f6i->fib6_dst.addr)) - dev = l3mdev_master_dev_rcu(dev); + dev = l3mdev_master_dev_rcu(dev) ? : + dev_net(dev)->loopback_dev; else if (!netif_is_l3_master(dev)) dev = dev_net(dev)->loopback_dev; /* last case is netif_is_l3_master(dev) is true in which -- 2.51.0