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Date: Thu, 22 Dec 2022 10:35:43 +0200 From: Tudor Ambarus <tudor.ambarus@...aro.org> To: stable@...r.kernel.org Cc: willemdebruijn.kernel@...il.com, mst@...hat.com, jasowang@...hat.com, edumazet@...gle.com, virtualization@...ts.linux-foundation.org, davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org, willemb@...gle.com, syzkaller@...glegroups.com, liuhangbin@...il.com, linux-kernel@...r.kernel.org, joneslee@...gle.com, Tudor Ambarus <tudor.ambarus@...aro.org> Subject: [PATCH 0/2] net/af_packet: Fix kernel BUG in __skb_gso_segment The series is intended for stable@...r.kernel.org # 5.4+ Syzkaller reported the following bug on linux-5.{4, 10, 15}.y: https://syzkaller.appspot.com/bug?id=ce5575575f074c33ff80d104f5baee26f22e95f5 The upstream commit that introduces this bug is: 1ed1d5921139 ("net: skip virtio_net_hdr_set_proto if protocol already set") Upstream fixes the bug with the following commits, one of which introduces new support: e9d3f80935b6 ("net/af_packet: make sure to pull mac header") dfed913e8b55 ("net/af_packet: add VLAN support for AF_PACKET SOCK_RAW GSO") The additional logic and risk backported seems manageable. The blammed commit introduces a kernel BUG in __skb_gso_segment for AF_PACKET SOCK_RAW GSO VLAN tagged packets. What happens is that virtio_net_hdr_set_proto() exists early as skb->protocol is already set to ETH_P_ALL. Then in packet_parse_headers() skb->protocol is set to ETH_P_8021AD, but neither the network header position is adjusted, nor the mac header is pulled. Thus when we get to validate the xmit skb and enter skb_mac_gso_segment(), skb->mac_len has value 14, but vlan_depth gets updated to 18 after skb_network_protocol() is called. This causes the BUG_ON from __skb_pull(skb, vlan_depth) to be hit, as the mac header has not been pulled yet. The fixes from upstream backported cleanly without conflicts. I updated the commit message of the first patch to describe the problem encountered, and added Cc, Fixes, Reported-by and Tested-by tags. For the second patch I just added Cc to stable indicating the versions to be fixed, and added my Tested and Signed-off-by tags. I tested the patches on linux-5.{4, 10, 15}.y. Eric Dumazet (1): net/af_packet: make sure to pull mac header Hangbin Liu (1): net/af_packet: add VLAN support for AF_PACKET SOCK_RAW GSO net/packet/af_packet.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) -- 2.34.1
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