syzbot


WARNING in nbd_add_socket

Status: upstream: reported C repro on 2026/06/21 06:23
Subsystems: nbd
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+6b85d1e39a5b8ed9a954@syzkaller.appspotmail.com
First crash: 4d10h, last: 19m
Cause bisection: failed (error log, bisect log)
  
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ID Workflow Result Correct Bug Created Started Finished Revision Error
548a523c-001c-4d68-9c08-fb7233502f5e assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in nbd_add_socket 2026/06/19 00:01 2026/06/19 00:01 2026/06/19 01:03 24486521e841016092c2967aa4c1f4c16238080e

			
		
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[syzbot] [nbd?] WARNING in nbd_add_socket 0 (1) 2026/06/21 06:23

Sample crash report:
netlink: 3936 bytes leftover after parsing attributes in process `syz.0.25'.
------------[ cut here ]------------
!sock_allow_reclassification(sk)
WARNING: drivers/block/nbd.c:1249 at nbd_reclassify_socket drivers/block/nbd.c:1249 [inline], CPU#0: syz.0.25/5992
WARNING: drivers/block/nbd.c:1249 at nbd_add_socket+0xf35/0x12c0 drivers/block/nbd.c:1293, CPU#0: syz.0.25/5992
Modules linked in:

CPU: 0 UID: 0 PID: 5992 Comm: syz.0.25 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:nbd_reclassify_socket drivers/block/nbd.c:1249 [inline]
RIP: 0010:nbd_add_socket+0xf35/0x12c0 drivers/block/nbd.c:1293
Code: f7 e8 6f b5 20 fc bf e0 01 00 00 49 03 3e 48 c7 c6 40 02 55 8c e8 2b a8 1b fb b8 f0 ff ff ff e9 b2 fd ff ff e8 ac 60 b5 fb 90 <0f> 0b 90 e9 16 f8 ff ff e8 5e 2e 97 05 44 89 e9 80 e1 07 fe c1 38
RSP: 0018:ffffc90002ef7160 EFLAGS: 00010293

RAX: ffffffff86109574 RBX: 1ffff1100651ddb9 RCX: ffff888020b68000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90002ef7250 R08: ffff888035af2bdf R09: 1ffff11006b5e57b
R10: dffffc0000000000 R11: ffffed1006b5e57c R12: ffff8880328eec00
R13: 1ffff920005dee38 R14: dffffc0000000000 R15: 0000000000000001
FS:  00007fcc9d5dd6c0(0000) GS:ffff88812527c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f81a8ab50f0 CR3: 0000000078780000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 nbd_genl_connect+0x133d/0x1c10 drivers/block/nbd.c:2254
 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x9b9/0xa20 net/socket.c:2684
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
 __sys_sendmsg net/socket.c:2770 [inline]
 __do_sys_sendmsg net/socket.c:2775 [inline]
 __se_sys_sendmsg net/socket.c:2773 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcc9df9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcc9d5dd028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fcc9e216090 RCX: 00007fcc9df9ce59
RDX: 0000000000004040 RSI: 0000200000000140 RDI: 0000000000000004
RBP: 00007fcc9e032d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcc9e216128 R14: 00007fcc9e216090 R15: 00007ffc8f827678
 </TASK>

Crashes (32):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/18 09:48 net b85966adbf5d b62b3ded .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/18 08:25 bpf e771677c937d b62b3ded .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING in nbd_add_socket
2026/06/18 09:31 bpf-next 66affa37cfac b62b3ded .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-bpf-next-kasan-gce WARNING in nbd_add_socket
2026/06/18 06:41 net b85966adbf5d b62b3ded .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/18 20:13 upstream e771677c937d a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in nbd_add_socket
2026/06/21 15:26 upstream 390d73adf896 43bfcdb0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in nbd_add_socket
2026/06/18 20:58 upstream e771677c937d a776b0d0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in nbd_add_socket
2026/06/18 13:06 upstream e771677c937d a776b0d0 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in nbd_add_socket
2026/06/17 06:15 upstream 6b5a2b7d9bc1 62cc6db3 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in nbd_add_socket
2026/06/21 16:34 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/21 08:11 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/21 01:25 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/20 13:37 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/20 04:39 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/20 03:35 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/20 01:50 net 96e7f9122aae 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/19 12:49 net 5c121ee63568 d7ffd47b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/19 09:56 net 5c121ee63568 d7ffd47b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/19 06:21 net 5c121ee63568 d7ffd47b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/18 19:34 net 7d8297e26b4e a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/18 07:23 bpf e771677c937d b62b3ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING in nbd_add_socket
2026/06/18 07:23 bpf e771677c937d b62b3ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-bpf-kasan-gce WARNING in nbd_add_socket
2026/06/18 05:33 net b85966adbf5d b62b3ded .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nbd_add_socket
2026/06/21 07:14 net-next b85966adbf5d 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/21 03:34 net-next b85966adbf5d 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/20 13:49 net-next b85966adbf5d 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/20 13:28 net-next b85966adbf5d 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/20 02:50 net-next b85966adbf5d 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/19 02:17 net-next b85966adbf5d a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/19 00:35 net-next b85966adbf5d a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/18 23:56 net-next b85966adbf5d a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
2026/06/18 18:11 net-next b85966adbf5d a776b0d0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nbd_add_socket
* Struck through repros no longer work on HEAD.