From: Eric Dumazet edumazet@google.com
[ Upstream commit 8e50ed774554f93d55426039b27b1e38d7fa64d8 ]
Drivers should not assume skb_mac_header(skb) == skb->data in their ndo_start_xmit().
Use skb_network_offset() and skb_transport_offset() which better describe what is needed in erspan_fb_xmit() and ip6erspan_tunnel_xmit()
syzbot reported: WARNING: CPU: 0 PID: 5083 at include/linux/skbuff.h:2873 skb_mac_header include/linux/skbuff.h:2873 [inline] WARNING: CPU: 0 PID: 5083 at include/linux/skbuff.h:2873 ip6erspan_tunnel_xmit+0x1d9c/0x2d90 net/ipv6/ip6_gre.c:962 Modules linked in: CPU: 0 PID: 5083 Comm: syz-executor406 Not tainted 6.3.0-rc2-syzkaller-00866-gd4671cb96fa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 RIP: 0010:skb_mac_header include/linux/skbuff.h:2873 [inline] RIP: 0010:ip6erspan_tunnel_xmit+0x1d9c/0x2d90 net/ipv6/ip6_gre.c:962 Code: 04 02 41 01 de 84 c0 74 08 3c 03 0f 8e 1c 0a 00 00 45 89 b4 24 c8 00 00 00 c6 85 77 fe ff ff 01 e9 33 e7 ff ff e8 b4 27 a1 f8 <0f> 0b e9 b6 e7 ff ff e8 a8 27 a1 f8 49 8d bf f0 0c 00 00 48 b8 00 RSP: 0018:ffffc90003b2f830 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 000000000000ffff RCX: 0000000000000000 RDX: ffff888021273a80 RSI: ffffffff88e1bd4c RDI: 0000000000000003 RBP: ffffc90003b2f9d8 R08: 0000000000000003 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000000 R12: ffff88802b28da00 R13: 00000000000000d0 R14: ffff88807e25b6d0 R15: ffff888023408000 FS: 0000555556a61300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e5b11eb6e8 CR3: 0000000027c1b000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __netdev_start_xmit include/linux/netdevice.h:4900 [inline] netdev_start_xmit include/linux/netdevice.h:4914 [inline] __dev_direct_xmit+0x504/0x730 net/core/dev.c:4300 dev_direct_xmit include/linux/netdevice.h:3088 [inline] packet_xmit+0x20a/0x390 net/packet/af_packet.c:285 packet_snd net/packet/af_packet.c:3075 [inline] packet_sendmsg+0x31a0/0x5150 net/packet/af_packet.c:3107 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg+0xde/0x190 net/socket.c:747 __sys_sendto+0x23a/0x340 net/socket.c:2142 __do_sys_sendto net/socket.c:2154 [inline] __se_sys_sendto net/socket.c:2150 [inline] __x64_sys_sendto+0xe1/0x1b0 net/socket.c:2150 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f123aaa1039 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc15d12058 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f123aaa1039 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000020000040 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f123aa648c0 R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
Fixes: 1baf5ebf8954 ("erspan: auto detect truncated packets.") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Simon Horman simon.horman@corigine.com Link: https://lore.kernel.org/r/20230320163427.8096-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/ip_gre.c | 4 ++-- net/ipv6/ip6_gre.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 52dbffb7bc2fd..317fdb9f47e88 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -525,7 +525,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev) truncate = true; }
- nhoff = skb_network_header(skb) - skb_mac_header(skb); + nhoff = skb_network_offset(skb); if (skb->protocol == htons(ETH_P_IP) && (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff)) truncate = true; @@ -534,7 +534,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev) int thoff;
if (skb_transport_header_was_set(skb)) - thoff = skb_transport_header(skb) - skb_mac_header(skb); + thoff = skb_transport_offset(skb); else thoff = nhoff + sizeof(struct ipv6hdr); if (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index fd4da1019e44c..85ec466b5735e 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -942,7 +942,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb, truncate = true; }
- nhoff = skb_network_header(skb) - skb_mac_header(skb); + nhoff = skb_network_offset(skb); if (skb->protocol == htons(ETH_P_IP) && (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff)) truncate = true; @@ -951,7 +951,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb, int thoff;
if (skb_transport_header_was_set(skb)) - thoff = skb_transport_header(skb) - skb_mac_header(skb); + thoff = skb_transport_offset(skb); else thoff = nhoff + sizeof(struct ipv6hdr); if (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff)