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Message-ID: <688bb9ca.a00a0220.26d0e1.0050.GAE@google.com>
Date: Thu, 31 Jul 2025 11:45:30 -0700
From: syzbot <syzbot+8aa80c6232008f7b957d@...kaller.appspotmail.com>
To: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com, 
	kuba@...nel.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] BUG: unable to handle kernel paging request in nsim_queue_free

Hello,

syzbot found the following issue on:

HEAD commit:    e8d780dcd957 Merge tag 'slab-for-6.17' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14382cf0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c99a414773e8e8dd
dashboard link: https://syzkaller.appspot.com/bug?extid=8aa80c6232008f7b957d
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-e8d780dc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9d67cb9a6476/vmlinux-e8d780dc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5b160fb5034b/bzImage-e8d780dc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8aa80c6232008f7b957d@...kaller.appspotmail.com

netdevsim netdevsim1 netdevsim2 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim1 netdevsim1 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim1 netdevsim0 (unregistering): unset [1, 0] type 2 family 0 port 6081 - 0
BUG: unable to handle page fault for address: ffff88809782c020
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 1b401067 P4D 1b401067 PUD 0 
Oops: Oops: 0002 [#1] SMP KASAN NOPTI
CPU: 3 UID: 0 PID: 8476 Comm: syz.1.251 Not tainted 6.16.0-syzkaller-06699-ge8d780dcd957 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:local_add arch/x86/include/asm/local.h:33 [inline]
RIP: 0010:u64_stats_add include/linux/u64_stats_sync.h:89 [inline]
RIP: 0010:dev_dstats_rx_dropped_add include/linux/netdevice.h:3027 [inline]
RIP: 0010:nsim_queue_free+0xba/0x120 drivers/net/netdevsim/netdev.c:714
Code: 07 77 6c 4a 8d 3c ed 20 7e f1 8d 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 46 4a 03 1c ed 20 7e f1 8d <4c> 01 63 20 be 00 02 00 00 48 8d 3d 00 00 00 00 e8 61 2f 58 fa 48
RSP: 0018:ffffc900044af150 EFLAGS: 00010286
RAX: dffffc0000000000 RBX: ffff88809782c000 RCX: 00000000000079c3
RDX: 1ffffffff1be2fc7 RSI: ffffffff8c15f380 RDI: ffffffff8df17e38
RBP: ffff88805f59d000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000003 R14: ffff88806ceb3d00 R15: ffffed100dfd308e
FS:  0000000000000000(0000) GS:ffff88809782c000(0063) knlGS:00000000f505db40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffff88809782c020 CR3: 000000006fc6a000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 nsim_queue_uninit drivers/net/netdevsim/netdev.c:993 [inline]
 nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1049 [inline]
 nsim_create+0xd0a/0x1260 drivers/net/netdevsim/netdev.c:1101
 __nsim_dev_port_add+0x435/0x7d0 drivers/net/netdevsim/dev.c:1438
 nsim_dev_port_add_all drivers/net/netdevsim/dev.c:1494 [inline]
 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1546 [inline]
 nsim_dev_reload_up+0x5b8/0x860 drivers/net/netdevsim/dev.c:1003
 devlink_reload+0x322/0x7c0 net/devlink/dev.c:474
 devlink_nl_reload_doit+0xe31/0x1410 net/devlink/dev.c:584
 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg net/socket.c:729 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2614
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668
 __sys_sendmsg+0x16d/0x220 net/socket.c:2700
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x3a0 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf708e579
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:00000000f505d55c EFLAGS: 00000296 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000080000080
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: ffff88809782c020
---[ end trace 0000000000000000 ]---
RIP: 0010:local_add arch/x86/include/asm/local.h:33 [inline]
RIP: 0010:u64_stats_add include/linux/u64_stats_sync.h:89 [inline]
RIP: 0010:dev_dstats_rx_dropped_add include/linux/netdevice.h:3027 [inline]
RIP: 0010:nsim_queue_free+0xba/0x120 drivers/net/netdevsim/netdev.c:714
Code: 07 77 6c 4a 8d 3c ed 20 7e f1 8d 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 46 4a 03 1c ed 20 7e f1 8d <4c> 01 63 20 be 00 02 00 00 48 8d 3d 00 00 00 00 e8 61 2f 58 fa 48
RSP: 0018:ffffc900044af150 EFLAGS: 00010286
RAX: dffffc0000000000 RBX: ffff88809782c000 RCX: 00000000000079c3
RDX: 1ffffffff1be2fc7 RSI: ffffffff8c15f380 RDI: ffffffff8df17e38
RBP: ffff88805f59d000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000003 R14: ffff88806ceb3d00 R15: ffffed100dfd308e
FS:  0000000000000000(0000) GS:ffff88809782c000(0063) knlGS:00000000f505db40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffff88809782c020 CR3: 000000006fc6a000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	77 6c                	ja     0x6e
   2:	4a 8d 3c ed 20 7e f1 	lea    -0x720e81e0(,%r13,8),%rdi
   9:	8d
   a:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  11:	fc ff df
  14:	48 89 fa             	mov    %rdi,%rdx
  17:	48 c1 ea 03          	shr    $0x3,%rdx
  1b:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
  1f:	75 46                	jne    0x67
  21:	4a 03 1c ed 20 7e f1 	add    -0x720e81e0(,%r13,8),%rbx
  28:	8d
* 29:	4c 01 63 20          	add    %r12,0x20(%rbx) <-- trapping instruction
  2d:	be 00 02 00 00       	mov    $0x200,%esi
  32:	48 8d 3d 00 00 00 00 	lea    0x0(%rip),%rdi        # 0x39
  39:	e8 61 2f 58 fa       	call   0xfa582f9f
  3e:	48                   	rex.W


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

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