Subject: [syzbot] kernel BUG in pskb_expand_head

From: syzbot <[email-masked]>
Date: Mon, 15 Nov 2021 00:38:25 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    debe436e77c7 Merge tag 'ext4_for_linus' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17cdbcf1b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dcce4e862d74e466
dashboard link: https://syzkaller.appspot.com/bug?extid=4c63f36709a642f801c5
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:1695!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 13268 Comm: syz-executor.1 Not tainted 5.15.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:pskb_expand_head+0xb28/0x1060 net/core/skbuff.c:1695
Code: 8d 75 ff e9 60 fe ff ff e8 75 dd 5a fa 48 c7 c6 a0 60 8c 8a 4c 89 f7 e8 c6 d6 8d fa 0f 0b e8 5f dd 5a fa 0f 0b e8 58 dd 5a fa <0f> 0b e8 51 dd 5a fa 41 81 cc 00 00 02 00 e9 f6 f5 ff ff e8 40 dd
RSP: 0018:ffffc90005a6f2e0 EFLAGS: 00010212
RAX: 0000000000030e8b RBX: ffff88801fa215c0 RCX: ffffc90020bf5000
RDX: 0000000000040000 RSI: ffffffff871c2298 RDI: 0000000000000003
RBP: 00000000ffffffbb R08: 0000000000000001 R09: ffff88801fa2169f
R10: ffffffff871c1842 R11: 0000000000000000 R12: 0000000000000a20
R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000
FS:  00007f39135d8700(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020004038 CR3: 0000000065ef5000 CR4: 0000000000150ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 __skb_pad+0x181/0x5f0 net/core/skbuff.c:1929
 __skb_put_padto include/linux/skbuff.h:3331 [inline]
 skb_put_padto include/linux/skbuff.h:3350 [inline]
 eth_skb_pad include/linux/etherdevice.h:584 [inline]
 e1000_xmit_frame+0x2de3/0x4650 drivers/net/ethernet/intel/e1000/e1000_main.c:3125
 __netdev_start_xmit include/linux/netdevice.h:4987 [inline]
 netdev_start_xmit include/linux/netdevice.h:5001 [inline]
 xmit_one net/core/dev.c:3590 [inline]
 dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3606
 sch_direct_xmit+0x19f/0xbc0 net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3817 [inline]
 __dev_queue_xmit+0x149c/0x3630 net/core/dev.c:4194
 llc_sap_action_send_test_c+0x22e/0x2c0 net/llc/llc_s_ac.c:144
 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+0x9f3/0x10b0 net/llc/af_llc.c:964
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 ____sys_sendmsg+0x331/0x810 net/socket.c:2409
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2463
 __sys_sendmmsg+0x195/0x470 net/socket.c:2549
 __do_sys_sendmmsg net/socket.c:2578 [inline]
 __se_sys_sendmmsg net/socket.c:2575 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2575
 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+0x44/0xae
RIP: 0033:0x7f3916062ae9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f39135d8188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f3916175f60 RCX: 00007f3916062ae9
RDX: 03fffffffffffeed RSI: 0000000020001380 RDI: 0000000000000005
RBP: 00007f39160bcf6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe4b72644f R14: 00007f39135d8300 R15: 0000000000022000
 </TASK>
Modules linked in:
---[ end trace 518f993fe030bf9b ]---
RIP: 0010:pskb_expand_head+0xb28/0x1060 net/core/skbuff.c:1695
Code: 8d 75 ff e9 60 fe ff ff e8 75 dd 5a fa 48 c7 c6 a0 60 8c 8a 4c 89 f7 e8 c6 d6 8d fa 0f 0b e8 5f dd 5a fa 0f 0b e8 58 dd 5a fa <0f> 0b e8 51 dd 5a fa 41 81 cc 00 00 02 00 e9 f6 f5 ff ff e8 40 dd
RSP: 0018:ffffc90005a6f2e0 EFLAGS: 00010212
RAX: 0000000000030e8b RBX: ffff88801fa215c0 RCX: ffffc90020bf5000
RDX: 0000000000040000 RSI: ffffffff871c2298 RDI: 0000000000000003
RBP: 00000000ffffffbb R08: 0000000000000001 R09: ffff88801fa2169f
R10: ffffffff871c1842 R11: 0000000000000000 R12: 0000000000000a20
R13: 0000000000000002 R14: 0000000000000001 R15: 0000000000000000
FS:  00007f39135d8700(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020004038 CR3: 0000000065ef5000 CR4: 0000000000150ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600

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