Greg KH
2023-Jan-04 12:43 UTC
[PATCH 0/2] net/af_packet: Fix kernel BUG in __skb_gso_segment
On Thu, Dec 22, 2022 at 10:35:43AM +0200, Tudor Ambarus wrote:> The series is intended for stable at vger.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(-)Now queued up, thanks. greg k-h