[syzbot] kernel BUG in llc_sap_action_send_xid_c

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    864db232 net: ipv6: check for validity before dereferencin..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=16377d16d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=daeff30c2474a60f
dashboard link: https://syzkaller.appspot.com/bug?extid=5e5a981ad7cc54c4b2b4
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=154f8e9ad00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16fe2fbed00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5e5a981ad7cc54c4b2b4@xxxxxxxxxxxxxxxxxxxxxxxxx

skbuff: skb_over_panic: text:ffffffff8717de50 len:692 put:3 head:ffff888025f6f000 data:ffff888025f6f00e tail:0x2c2 end:0x2c0 dev:bond0
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:109!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8372 Comm: syz-executor543 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:109
Code: f8 4c 8b 4c 24 10 8b 4b 70 41 56 45 89 e8 4c 89 e2 41 57 48 89 ee 48 c7 c7 40 b2 65 8a ff 74 24 10 ff 74 24 20 e8 e7 c0 c4 ff <0f> 0b e8 d2 e0 75 f8 4c 8b 64 24 18 e8 c8 87 b9 f8 48 c7 c1 80 be
RSP: 0018:ffffc9000132f7b8 EFLAGS: 00010282
RAX: 0000000000000086 RBX: ffff888012a91140 RCX: 0000000000000000
RDX: ffff888021d6d4c0 RSI: ffffffff815c4d75 RDI: fffff52000265ee9
RBP: ffffffff8a65bec0 R08: 0000000000000086 R09: 0000000000000000
R10: ffffffff815bdb0e R11: 0000000000000000 R12: ffffffff8717de50
R13: 0000000000000003 R14: ffff88801aa24000 R15: 00000000000002c0
FS:  0000000001d53300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055acdca69398 CR3: 0000000020a7b000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 skb_over_panic net/core/skbuff.c:114 [inline]
 skb_put.cold+0x24/0x24 net/core/skbuff.c:1914
 llc_pdu_init_as_xid_cmd include/net/llc_pdu.h:377 [inline]
 llc_sap_action_send_xid_c+0x240/0x380 net/llc/llc_s_ac.c:84
 llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline]
 llc_sap_next_state net/llc/llc_sap.c:182 [inline]
 llc_sap_state_process+0x22a/0x4f0 net/llc/llc_sap.c:209
 llc_ui_sendmsg+0x9ee/0x1040 net/llc/af_llc.c:964
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 ____sys_sendmsg+0x331/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmmsg+0x195/0x470 net/socket.c:2490
 __do_sys_sendmmsg net/socket.c:2519 [inline]
 __se_sys_sendmmsg net/socket.c:2516 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2516
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43f329
Code: 28 c3 e8 2a 14 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:00007ffc10253fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043f329
RDX: 0000000000000006 RSI: 0000000020005bc0 RDI: 0000000000000003
RBP: 0000000000403310 R08: 0000000000400488 R09: 0000000000400488
R10: 0000000004000000 R11: 0000000000000246 R12: 00000000004033a0
R13: 0000000000000000 R14: 00000000004ad018 R15: 0000000000400488
Modules linked in:
---[ end trace 4d95aeb9a24efeaa ]---
RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:109
Code: f8 4c 8b 4c 24 10 8b 4b 70 41 56 45 89 e8 4c 89 e2 41 57 48 89 ee 48 c7 c7 40 b2 65 8a ff 74 24 10 ff 74 24 20 e8 e7 c0 c4 ff <0f> 0b e8 d2 e0 75 f8 4c 8b 64 24 18 e8 c8 87 b9 f8 48 c7 c1 80 be
RSP: 0018:ffffc9000132f7b8 EFLAGS: 00010282
RAX: 0000000000000086 RBX: ffff888012a91140 RCX: 0000000000000000
RDX: ffff888021d6d4c0 RSI: ffffffff815c4d75 RDI: fffff52000265ee9
RBP: ffffffff8a65bec0 R08: 0000000000000086 R09: 0000000000000000
R10: ffffffff815bdb0e R11: 0000000000000000 R12: ffffffff8717de50
R13: 0000000000000003 R14: ffff88801aa24000 R15: 00000000000002c0
FS:  0000000001d53300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055acdca69398 CR3: 0000000020a7b000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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