Re: [syzbot] upstream boot error: WARNING in netlink_ack

[Dmitry Vyukov]

On Tue, 4 Oct 2022 at 10:27, syzbot
<syzbot+3a080099974c271cd7e9@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    725737e7c21d Merge tag 'statx-dioalign-for-linus' of git:/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10257034880000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=486af5e221f55835
> dashboard link: https://syzkaller.appspot.com/bug?extid=3a080099974c271cd7e9
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3a080099974c271cd7e9@xxxxxxxxxxxxxxxxxxxxxxxxx

+linux-hardening

> ------------[ cut here ]------------
> memcpy: detected field-spanning write (size 28) of single field "&errmsg->msg" at net/netlink/af_netlink.c:2447 (size 16)
> WARNING: CPU: 3 PID: 3351 at net/netlink/af_netlink.c:2447 netlink_ack+0x8ac/0xb10 net/netlink/af_netlink.c:2447
> Modules linked in:
> CPU: 3 PID: 3351 Comm: dhcpcd Not tainted 6.0.0-syzkaller-00593-g725737e7c21d #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
> RIP: 0010:netlink_ack+0x8ac/0xb10 net/netlink/af_netlink.c:2447
> Code: fa ff ff e8 36 c3 e5 f9 b9 10 00 00 00 4c 89 ee 48 c7 c2 20 3f fb 8a 48 c7 c7 80 3f fb 8a c6 05 e8 98 34 06 01 e8 26 77 a6 01 <0f> 0b e9 3a fa ff ff 41 be 00 01 00 00 41 bd 14 00 00 00 e9 ea fd
> RSP: 0018:ffffc900220e7758 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff88801a798a80 RCX: 0000000000000000
> RDX: ffff8880151c0180 RSI: ffffffff81611cb8 RDI: fffff5200441cedd
> RBP: ffff88801ed850c0 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000080000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 000000000000001c R14: ffff88801ec8e400 R15: ffff88801ec8e414
> FS:  00007faef0af8740(0000) GS:ffff88802cb00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fff6adbe000 CR3: 0000000027683000 CR4: 0000000000150ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  netlink_rcv_skb+0x33d/0x420 net/netlink/af_netlink.c:2507
>  genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
>  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
>  netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
>  netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
>  sock_sendmsg_nosec net/socket.c:714 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:734
>  ____sys_sendmsg+0x712/0x8c0 net/socket.c:2482
>  ___sys_sendmsg+0x110/0x1b0 net/socket.c:2536
>  __sys_sendmsg+0xf3/0x1c0 net/socket.c:2565
>  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+0x63/0xcd
> RIP: 0033:0x7faef0bf0163
> Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 89 54 24 1c 48
> RSP: 002b:00007fff6adbdc48 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007faef0bf0163
> RDX: 0000000000000000 RSI: 00007fff6adbdc90 RDI: 0000000000000010
> RBP: 00007fff6adc1ed8 R08: 0000000000000000 R09: 0000000000000000
> R10: 00007faef0c6ffc0 R11: 0000000000000246 R12: 0000000000000010
> R13: 00007fff6adc1cf0 R14: 0000000000000000 R15: 000055e5ebce0290
>  </TASK>
>
>
> ---
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>
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