skb frag: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb frag: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 ------------[ cut here ]------------ offset+2 (11561) > skb_headlen() (116) WARNING: CPU: 2 PID: 16637 at net/core/dev.c:3331 skb_checksum_help+0x5dc/0x730 net/core/dev.c:3331 Modules linked in: CPU: 2 PID: 16637 Comm: syz-executor.1 Not tainted 6.6.0-rc7-syzkaller-00018-gd88520ad73b7 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:skb_checksum_help+0x5dc/0x730 net/core/dev.c:3331 Code: 48 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 4f 01 00 00 44 89 e2 2b 53 74 4c 89 ee 48 c7 c7 40 92 a2 8b e8 44 e5 1c f9 <0f> 0b e9 8f fe ff ff e8 78 99 ac f9 e9 53 fa ff ff 48 89 ef e8 ab RSP: 0018:ffffc9002954f078 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff8880009eea00 RCX: ffffc900073c1000 RDX: 0000000000040000 RSI: ffffffff814e00c6 RDI: 0000000000000001 RBP: ffff8880009eea74 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000020626b73 R12: 0000000000002d51 R13: 0000000000002d29 R14: ffff8880009eea70 R15: 0000000000002d27 FS: 0000000000000000(0000) GS:ffff88802c800000(0063) knlGS:00000000f7f30b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 000000002000d000 CR3: 00000000270ad000 CR4: 0000000000350ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ip_do_fragment+0xa1b/0x18b0 net/ipv4/ip_output.c:775 ip_fragment.constprop.0+0x161/0x230 net/ipv4/ip_output.c:582 ip_finish_output_gso net/ipv4/ip_output.c:284 [inline] __ip_finish_output net/ipv4/ip_output.c:306 [inline] __ip_finish_output+0x49a/0x640 net/ipv4/ip_output.c:293 ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:321 NF_HOOK_COND include/linux/netfilter.h:293 [inline] ip_mc_output+0x1dd/0x6a0 net/ipv4/ip_output.c:418 dst_output include/net/dst.h:458 [inline] ip_local_out+0xaf/0x190 net/ipv4/ip_output.c:127 iptunnel_xmit+0x61a/0x9e0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1e4f/0x3370 net/ipv4/ip_tunnel.c:831 ipgre_xmit+0x63c/0x910 net/ipv4/ip_gre.c:662 __netdev_start_xmit include/linux/netdevice.h:4889 [inline] netdev_start_xmit include/linux/netdevice.h:4903 [inline] xmit_one net/core/dev.c:3573 [inline] dev_hard_start_xmit+0x13d/0x6c0 net/core/dev.c:3589 __dev_queue_xmit+0x9b4/0x3d60 net/core/dev.c:4369 dev_queue_xmit include/linux/netdevice.h:3082 [inline] packet_xmit+0x257/0x380 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3087 [inline] packet_sendmsg+0x24d9/0x5580 net/packet/af_packet.c:3119 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0xd5/0x180 net/socket.c:745 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2558 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2612 __sys_sendmsg+0x117/0x1e0 net/socket.c:2641 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] __do_fast_syscall_32+0x61/0xe0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 RIP: 0023:0xf7f35579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f7f305ac EFLAGS: 00000292 ORIG_RAX: 0000000000000172 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020002ac0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi