syzbot


WARNING in skb_tunnel_check_pmtu

Status: fixed on 2023/02/24 13:50
Subsystems: net
[Documentation on labels]
Fix commit: 853a76148802 tunnels: do not assume mac header is set in skb_tunnel_check_pmtu()
First crash: 734d, last: 728d
Cause bisection: introduced by (bisect log) :
commit f9aefd6b2aa38b9787d2705f0f1161dfd23cdb8f
Author: Eric Dumazet <edumazet@google.com>
Date: Mon Jun 20 09:30:17 2022 +0000

  net: warn if mac header was not set

Crash: WARNING in skb_tunnel_check_pmtu (log)
Repro: C syz .config
  

Sample crash report:
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3617 at include/linux/skbuff.h:2784 skb_mac_header_len include/linux/skbuff.h:2784 [inline]
WARNING: CPU: 0 PID: 3617 at include/linux/skbuff.h:2784 skb_tunnel_check_pmtu+0x5de/0x2f90 net/ipv4/ip_tunnel_core.c:413
Modules linked in:
CPU: 0 PID: 3617 Comm: syz-executor361 Not tainted 5.19.0-rc2-syzkaller-00443-g8720bd951b8e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:skb_mac_header_len include/linux/skbuff.h:2784 [inline]
RIP: 0010:skb_tunnel_check_pmtu+0x5de/0x2f90 net/ipv4/ip_tunnel_core.c:413
Code: 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 84 b9 fe ff ff 4c 89 ff e8 7c 0f d7 f9 e9 ac fe ff ff e8 c2 13 8a f9 <0f> 0b e9 28 fc ff ff e8 b6 13 8a f9 48 8b 54 24 70 48 b8 00 00 00
RSP: 0018:ffffc90002faf520 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888075ae4780 RCX: 0000000000000000
RDX: ffff8880272f8000 RSI: ffffffff87f05e3e RDI: 0000000000000003
RBP: ffffc90002faf650 R08: 0000000000000003 R09: 000000000000ffff
R10: 000000000000ffff R11: 0000000000000000 R12: 000000000000ffff
R13: 0000000000000000 R14: 000000000000ffcd R15: 000000000000000e
FS:  00005555568b8300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 0000000073a76000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 geneve_xmit_skb drivers/net/geneve.c:927 [inline]
 geneve_xmit+0xcf8/0x35d0 drivers/net/geneve.c:1107
 __netdev_start_xmit include/linux/netdevice.h:4805 [inline]
 netdev_start_xmit include/linux/netdevice.h:4819 [inline]
 __dev_direct_xmit+0x500/0x730 net/core/dev.c:4309
 dev_direct_xmit include/linux/netdevice.h:3007 [inline]
 packet_direct_xmit+0x1b8/0x2c0 net/packet/af_packet.c:282
 packet_snd net/packet/af_packet.c:3073 [inline]
 packet_sendmsg+0x21f4/0x55d0 net/packet/af_packet.c:3104
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:734
 ____sys_sendmsg+0x6eb/0x810 net/socket.c:2489
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2543
 __sys_sendmsg net/socket.c:2572 [inline]
 __do_sys_sendmsg net/socket.c:2581 [inline]
 __se_sys_sendmsg net/socket.c:2579 [inline]
 __x64_sys_sendmsg+0x132/0x220 net/socket.c:2579
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f71c5f48919
Code: 28 c3 e8 4a 15 00 00 66 2e 0f 1f 84 00 00 00 00 00 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:00007fffee9c0578 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fffee9c0588 RCX: 00007f71c5f48919
RDX: 0000000000000000 RSI: 0000000020000a00 RDI: 0000000000000003
RBP: 0000000000000003 R08: bb1414ac00000000 R09: bb1414ac00000000
R10: 0000000000000004 R11: 0000000000000246 R12: 00007fffee9c0590
R13: 00007fffee9c0584 R14: 0000000000000003 R15: 0000000000000000
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/06/21 19:37 net-next-old 8720bd951b8e 0fc5c330 .config strace log report syz C ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/27 16:14 net-next-old c83bc86a0596 a371c43c .config console log report info ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/22 21:53 net-next-old 6dd4142fb5a9 912f5df7 .config console log report info ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/22 21:21 net-next-old 6dd4142fb5a9 912f5df7 .config console log report info ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/22 14:02 net-next-old a80d8fb70cc7 0fc5c330 .config console log report info ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/22 07:45 net-next-old 8720bd951b8e 0fc5c330 .config console log report info ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/21 18:43 net-next-old 8720bd951b8e 0fc5c330 .config console log report info ci-upstream-net-kasan-gce WARNING in skb_tunnel_check_pmtu
2022/06/27 16:53 linux-next aab35c3d5112 a371c43c .config console log report info ci-upstream-linux-next-kasan-gce-root WARNING in skb_tunnel_check_pmtu
* Struck through repros no longer work on HEAD.