net: nsh: Use correct mac_offset to unwind gso skb in nsh_gso_segment()
stable inclusion from stable-v4.19.283 commit d2309e0cb27b6871b273fbc1725e93be62570d86 category: bugfix bugzilla: 188702, https://gitee.com/openeuler/kernel/issues/I7DUPI CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d2309e0cb27b6871b273fbc1725e93be62570d86 -------------------------------- [ Upstream commit c83b4938 ] As the call trace shows, skb_panic was caused by wrong skb->mac_header in nsh_gso_segment(): invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 3 PID: 2737 Comm: syz Not tainted 6.3.0-next-20230505 #1 RIP: 0010:skb_panic+0xda/0xe0 call Trace: skb_push+0x91/0xa0 nsh_gso_segment+0x4f3/0x570 skb_mac_gso_segment+0x19e/0x270 __skb_gso_segment+0x1e8/0x3c0 validate_xmit_skb+0x452/0x890 validate_xmit_skb_list+0x99/0xd0 sch_direct_xmit+0x294/0x7c0 __dev_queue_xmit+0x16f0/0x1d70 packet_xmit+0x185/0x210 packet_snd+0xc15/0x1170 packet_sendmsg+0x7b/0xa0 sock_sendmsg+0x14f/0x160 The root cause is: nsh_gso_segment() use skb->network_header - nhoff to reset mac_header in skb_gso_error_unwind() if inner-layer protocol gso fails. However, skb->network_header may be reset by inner-layer protocol gso function e.g. mpls_gso_segment. skb->mac_header reset by the inaccurate network_header will be larger than skb headroom. nsh_gso_segment nhoff = skb->network_header - skb->mac_header; __skb_pull(skb,nsh_len) skb_mac_gso_segment mpls_gso_segment skb_reset_network_header(skb);//skb->network_header+=nsh_len return -EINVAL; skb_gso_error_unwind skb_push(skb, nsh_len); skb->mac_header = skb->network_header - nhoff; // skb->mac_header > skb->headroom, cause skb_push panic Use correct mac_offset to restore mac_header and get rid of nhoff. Fixes: c411ed85 ("nsh: add GSO support") Reported-by: syzbot+632b5d9964208bfef8c0@syzkaller.appspotmail.com Suggested-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDong Chenchen <dongchenchen2@huawei.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NSasha Levin <sashal@kernel.org> Signed-off-by: NDong Chenchen <dongchenchen2@huawei.com> Reviewed-by: NYue Haibing <yuehaibing@huawei.com> Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>
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