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 BFB213FE359; Wed, 30 Sep 2026 19:06:22 +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=1790795184; cv=none; b=e9GXwZhtEiKuV1Z6Vdj0soLVM0nUVqtSa0a4fHw9vvU0ozsTVKHbr3Ac/Q1NVeBTS/gXg3va5oCYs8u40l2LORrMwo16JcAb+XDhLyg+B9I9QQBRhfCMAGchDYyudcWYXsRQ053CWzNo4Epdi8RHFrKZLR/UoGrGLv4dJVLH+G0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795184; c=relaxed/simple; bh=MSrZeKYol6bXkCGpHca7j9U32kSebs54rqek/b6OxTI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=py9Wv0GIT6qzay6k1CmEz6Ca1Ab6z5Cn8h+XkNuwaJhQ4yMkJG74PzxMVmOP/N7A2owe3SbhgQMbAYFNn2cbevRLA3XF+gMrSmuQoz+N+0SbZPSpTLQKRwPNfNCXcLEtvDGSr2AFl+taRcUWYWa3pXwDeMJ9CNB0q8dcdOx3n+g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=A6Wya8EL; 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="A6Wya8EL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2ACE61F0089A; Wed, 30 Sep 2026 19:06:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790795182; bh=EnB9pa/wb059ERZCSl/eDQsN3m4X8ClWGlj3RNvJW1Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=A6Wya8EL5svLDWOQmXkplfSuh3bLAkjZ5EiofqbVXLIpS6USshFYQD02JS2xfm8bY 4HHTKNcc119uFIAbewX3F9A9c0x88RQ2IR0oAUWcMsm3VGaCZ+Wd1hlSvPkmd4JKfw i+clwyi361OntXlpB/SukULvvtAk2Er/rmbN1jf8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shuangpeng Bai , Davide Caratti , Eric Dumazet , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 0427/1193] ip6_gre: check tunnel info before xmit in ip6gre_tunnel_xmit Date: Wed, 30 Sep 2026 17:18:31 +0200 Message-ID: <20260930152443.685855150@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 97cc84dad1d7f68a36b71b69b361d88482707673 ] Shuangpeng Bai reported a KASAN slab-use-after-free in ip6gre_tunnel_xmit(). The precise KASAN bug was caused by ip6_tnl_xmit() consuming the skb during headroom expansion and returning an error, while ip6gre_tunnel_xmit() still held the stale pointer and called skb_tunnel_info_txcheck(skb) at tx_err. That specific bug was fixed by commit 87f21b59ddc6 ("ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()"). However, calling skb_tunnel_info_txcheck(skb) at the tx_err label after the transmission attempt remains problematic: Downstream helpers like ip6_tnl_xmit() call skb_scrub_packet(), which drops the skb's metadata_dst before transmission. If an error occurs later during transmit, inspecting skb at tx_err sees a scrubbed dst and misclassifies tx_errors vs tx_dropped. Commit e5f7e211b6aa ("ip6gre: avoid tx_error when sending MLD/DAD on external tunnels") already handled this correctly in ip6erspan_tunnel_xmit() by checking and caching tun_info before transmit. Align ip6gre_tunnel_xmit() with ip6erspan_tunnel_xmit() by caching tun_info before xmit and checking it at tx_err. Fixes: e5f7e211b6aa ("ip6gre: avoid tx_error when sending MLD/DAD on external tunnels") Reported-by: Shuangpeng Bai Closes: https://lore.kernel.org/netdev/20260819062224.3197349-1-shuangpeng.kernel@gmail.com/ Cc: Davide Caratti Signed-off-by: Eric Dumazet Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260828103731.1951815-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv6/ip6_gre.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index ef94bce1d2d55..54fd270edc810 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -897,6 +897,7 @@ static int ip6gre_xmit_other(struct sk_buff *skb, struct net_device *dev) static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) { + struct ip_tunnel_info *tun_info = NULL; struct ip6_tnl *t = netdev_priv(dev); __be16 payload_protocol; int ret; @@ -907,6 +908,9 @@ static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb, if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr)) goto tx_err; + if (t->parms.collect_md) + tun_info = skb_tunnel_info_txcheck(skb); + payload_protocol = skb_protocol(skb, true); switch (payload_protocol) { case htons(ETH_P_IP): @@ -926,7 +930,7 @@ static netdev_tx_t ip6gre_tunnel_xmit(struct sk_buff *skb, return NETDEV_TX_OK; tx_err: - if (!t->parms.collect_md || !IS_ERR(skb_tunnel_info_txcheck(skb))) + if (!IS_ERR(tun_info)) DEV_STATS_INC(dev, tx_errors); DEV_STATS_INC(dev, tx_dropped); kfree_skb(skb); -- 2.53.0