From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794590979; b=SDgfXpvjZSuuVRD9yO6pJmY+7SGDkpbzQXvxtURpiKKwva0x4afqiiwXgFOmCFB6PW+S D5D3/j6wprCoW02SppVEFH7/qS7VPX7OCiUYnr1OxeacgZhK6VHwJ7HNGXe+ya9iYOHjE oKQeS8qLTMbxaAcnl+CredYdPdMPw2XgTHfFloFmVOKGXNeEbz7H4fP5uOJTkcvfRBHSX 0/gCXt8/iJuaGJbMa0Y6pzMI65khXzge8ikPNStrqxa+36uky5W1FNMUMfa3Tc5FKPZKJ yOMhiqJR4PW1idwbAJLUhPH5l1IczB5fMHHsWMOvYp9XnDq9/sL1Srr9PlBy8/3oMKA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794590979; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=pMHS05qVVvzdzob7yRKG5zLViaU3ogZutD4mJAkUcvM=; b=VIpTkLp645qzul8c3L3LbXdfnLYMTWMGa/DDXhpTu6m2nGiBpZ7KUxjN7zK9DThyjNE+ OS5AcNjn4Hz5S7d7FGi1SSyd/Ifcqjjtp0OWTTrTjXo/7/K2pObFcdnVk8kiZV64nkxod oggwZltKPL5G1JhuNg+OKAnMjMiccdsXIqptHn8AmOp9uOwVe3eFXgbqqE5Aj/ee0yHCZ oF64+3MW9ZV9b74Noandx8+DZK2lhxSVz9/ovT+hwe1HZLqw2WRLpLhvFVvfuCMeUU5+6 9JdygJO8LxLlrixicbQOAONIKf60Ty4gPAy7MPykI6OdxiOa/IYqBukwzwV05IFIiBw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=jhutG6KV; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF17E60703CB; Fri, 13 Nov 2026 17:29:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=jhutG6KV Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B6571F000C5; Fri, 13 Nov 2026 17:29:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794590978; bh=pMHS05qVVvzdzob7yRKG5zLViaU3ogZutD4mJAkUcvM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jhutG6KVj7VDySkQACxjfqwweD0p4T+ecckkupJ9WvQ0rapyKBqkZHSWsUWntCIEw cLeOk15tVqUmsJB3Z4lJFT38w6gXZNf+rZsHpUvPZOdQppFqwQ7D3d5b+SFZ1okGRe xmRZUxM4PKPKklWKgDl19/nMtuxTTi507DE3Gbe8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+9bda1b9fbb7fbdf9b62b@syzkaller.appspotmail.com, Yun Zhou , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 156/670] net: erspan: set lltx to avoid sch_direct_xmit deadlock Date: Fri, 13 Nov 2026 10:45:20 -0500 Message-ID: <20261113153817.428085998@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yun Zhou [ Upstream commit 2d36ec73836e83175deb467fd494c61006107e5d ] The ERSPAN xmit path re-enters the network stack, causing nested acquisition of _xmit_lock on the underlay device while already holding the ERSPAN device's _xmit_lock, creating an ABBA deadlock. This happens for both IPv4 ERSPAN (erspan_xmit() -> ip_tunnel_xmit()) and IPv6 ERSPAN (ip6erspan_tunnel_xmit() -> ip6_tnl_xmit()): sch_direct_xmit [lock erspan] -> erspan_xmit -> ip_tunnel_xmit -> ip_output -> __dev_queue_xmit -> sch_direct_xmit [lock underlay] sch_direct_xmit [lock erspan] -> ip6erspan_tunnel_xmit -> ip6_tnl_xmit -> ip6_output -> __dev_queue_xmit -> sch_direct_xmit [lock underlay] Set dev->lltx = true so HARD_TX_LOCK() skips the spinlock for ERSPAN. This is safe as the ERSPAN xmit path has no shared mutable state: o_seqno is atomic, TX stats are per-CPU u64_stats, dst_cache is per-CPU, and o_flags is no longer modified in the xmit path since commit 9958e69b9893 ("gre: fix ERSPAN o_flags race/corruption in xmit and fill_info"). GRETAP, the sibling device with identical xmit structure, already sets lltx. Reported-by: syzbot+9bda1b9fbb7fbdf9b62b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9bda1b9fbb7fbdf9b62b Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN") Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support") Cc: stable@vger.kernel.org # 9958e69b9893 ("gre: fix ERSPAN o_flags race/corruption in xmit and fill_info") Cc: stable@vger.kernel.org Signed-off-by: Yun Zhou Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20261008093824.119453-1-yun.zhou@windriver.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/ip_gre.c | 1 + net/ipv6/ip6_gre.c | 1 + 2 files changed, 2 insertions(+) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 5bf6c6777c348..f4a269938340a 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1362,6 +1362,7 @@ static int erspan_tunnel_init(struct net_device *dev) dev->features |= GRE_FEATURES; dev->hw_features |= GRE_FEATURES; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; + dev->lltx = true; netif_keep_dst(dev); return ip_tunnel_init(dev); diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 7cf429f11a1d0..9cb3c1fea4c91 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1902,6 +1902,7 @@ static int ip6erspan_tap_init(struct net_device *dev) dev->mtu -= 8; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; + dev->lltx = true; ip6erspan_tnl_link_config(tunnel, 1); netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL); -- 2.53.0