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 D3718611B for ; Sun, 28 May 2023 19:44:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DFC4C433D2; Sun, 28 May 2023 19:44:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685303086; bh=I0gRVigCHeU5plZqCKqUw+xQMB4LE+7cQh0hh8fi06E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o1Mw3R1fkRhhxsB0GgWuWZRyVLKFaW1MI9P3No/7VycZ20KnS1+6JK1zwYVzsw1ao UORFKiCwhfxUsNEsHfh6EzAEHvYl7L85XEcshLrN7XjmKrH71OU494Tq+s0DUpwTfg e5ldAh5ozq+KXDcYqMP5Y61Eik7pwlTHktAyYf/s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 5.10 120/211] vlan: fix a potential uninit-value in vlan_dev_hard_start_xmit() Date: Sun, 28 May 2023 20:10:41 +0100 Message-Id: <20230528190846.539779588@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190843.514829708@linuxfoundation.org> References: <20230528190843.514829708@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Eric Dumazet [ Upstream commit dacab578c7c6cd06c50c89dfa36b0e0f10decd4e ] syzbot triggered the following splat [1], sending an empty message through pppoe_sendmsg(). When VLAN_FLAG_REORDER_HDR flag is set, vlan_dev_hard_header() does not push extra bytes for the VLAN header, because vlan is offloaded. Unfortunately vlan_dev_hard_start_xmit() first reads veth->h_vlan_proto before testing (vlan->flags & VLAN_FLAG_REORDER_HDR). We need to swap the two conditions. [1] BUG: KMSAN: uninit-value in vlan_dev_hard_start_xmit+0x171/0x7f0 net/8021q/vlan_dev.c:111 vlan_dev_hard_start_xmit+0x171/0x7f0 net/8021q/vlan_dev.c:111 __netdev_start_xmit include/linux/netdevice.h:4883 [inline] netdev_start_xmit include/linux/netdevice.h:4897 [inline] xmit_one net/core/dev.c:3580 [inline] dev_hard_start_xmit+0x253/0xa20 net/core/dev.c:3596 __dev_queue_xmit+0x3c7f/0x5ac0 net/core/dev.c:4246 dev_queue_xmit include/linux/netdevice.h:3053 [inline] pppoe_sendmsg+0xa93/0xb80 drivers/net/ppp/pppoe.c:900 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555 __sys_sendmmsg+0x411/0xa50 net/socket.c:2641 __do_sys_sendmmsg net/socket.c:2670 [inline] __se_sys_sendmmsg net/socket.c:2667 [inline] __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2667 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Uninit was created at: slab_post_alloc_hook+0x12d/0xb60 mm/slab.h:774 slab_alloc_node mm/slub.c:3452 [inline] kmem_cache_alloc_node+0x543/0xab0 mm/slub.c:3497 kmalloc_reserve+0x148/0x470 net/core/skbuff.c:520 __alloc_skb+0x3a7/0x850 net/core/skbuff.c:606 alloc_skb include/linux/skbuff.h:1277 [inline] sock_wmalloc+0xfe/0x1a0 net/core/sock.c:2583 pppoe_sendmsg+0x3af/0xb80 drivers/net/ppp/pppoe.c:867 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555 __sys_sendmmsg+0x411/0xa50 net/socket.c:2641 __do_sys_sendmmsg net/socket.c:2670 [inline] __se_sys_sendmmsg net/socket.c:2667 [inline] __x64_sys_sendmmsg+0xbc/0x120 net/socket.c:2667 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd CPU: 0 PID: 29770 Comm: syz-executor.0 Not tainted 6.3.0-rc6-syzkaller-gc478e5b17829 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/8021q/vlan_dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c index 929f85c6cf112..8edac9307868a 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -108,8 +108,8 @@ static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb, * NOTE: THIS ASSUMES DIX ETHERNET, SPECIFICALLY NOT SUPPORTING * OTHER THINGS LIKE FDDI/TokenRing/802.3 SNAPs... */ - if (veth->h_vlan_proto != vlan->vlan_proto || - vlan->flags & VLAN_FLAG_REORDER_HDR) { + if (vlan->flags & VLAN_FLAG_REORDER_HDR || + veth->h_vlan_proto != vlan->vlan_proto) { u16 vlan_tci; vlan_tci = vlan->vlan_id; vlan_tci |= vlan_dev_get_egress_qos_mask(dev, skb->priority); -- 2.39.2