syzbot
general protection fault in dummy_queue
Status:
premoderation: reported on 2026/07/25 09:31
Reported-by: syzbot+3971fdeca744f327e379@syzkaller.appspotmail.com
First crash: 6d11h, last: 12h33m
Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 0 PID: 4025 Comm: kworker/0:7 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:dummy_queue+0x1b7/0x870 drivers/usb/gadget/udc/dummy_hcd.c:714
Code: fc ff df 80 3c 08 00 74 08 4c 89 e7 e8 12 56 7f fe 4d 8b 24 24 49 83 c4 48 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 80 05 00 00 45 8b 24 24 44 89 e6 83 e6 02
RSP: 0018:ffffc90000f97000 EFLAGS: 00010206
RAX: 0000000000000009 RBX: ffff888133872310 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000005
RBP: ffffc90000f97078 R08: ffff88810dc486a3 R09: 1ffff11021b890d4
R10: dffffc0000000000 R11: ffffed1021b890d5 R12: 0000000000000048
R13: ffff888133872300 R14: 1ffff1102670e460 R15: ffff88810b70cc90
FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2eae12 CR3: 00000001266e5000 CR4: 00000000003506b0
Call Trace:
<TASK>
usb_ep_queue+0xce/0x210 drivers/usb/gadget/udc/core.c:288
eth_start_xmit+0x811/0xd40 drivers/usb/gadget/function/u_ether.c:589
__netdev_start_xmit include/linux/netdevice.h:5064 [inline]
netdev_start_xmit include/linux/netdevice.h:5078 [inline]
xmit_one net/core/dev.c:3670 [inline]
dev_hard_start_xmit+0x245/0x680 net/core/dev.c:3686
sch_direct_xmit+0x279/0x9c0 net/sched/sch_generic.c:345
__dev_xmit_skb net/core/dev.c:3905 [inline]
__dev_queue_xmit+0x14f1/0x2d60 net/core/dev.c:4274
dev_queue_xmit+0x17/0x20 net/core/dev.c:4355
neigh_hh_output include/net/neighbour.h:501 [inline]
neigh_output include/net/neighbour.h:515 [inline]
ip6_finish_output2+0x1097/0x1790 net/ipv6/ip6_output.c:130
__ip6_finish_output+0x621/0x7e0 net/ipv6/ip6_output.c:201
ip6_finish_output+0x31/0x220 net/ipv6/ip6_output.c:211
NF_HOOK_COND include/linux/netfilter.h:294 [inline]
ip6_output+0x1fa/0x410 net/ipv6/ip6_output.c:234
dst_output include/net/dst.h:453 [inline]
NF_HOOK include/linux/netfilter.h:305 [inline]
mld_sendpack+0x68d/0xba0 net/ipv6/mcast.c:1825
mld_send_initial_cr+0x1c0/0x320 net/ipv6/mcast.c:2244
ipv6_mc_dad_complete+0x87/0x450 net/ipv6/mcast.c:2252
addrconf_dad_completed+0x73d/0xe20 net/ipv6/addrconf.c:4282
addrconf_dad_work+0xc4c/0x1510 net/ipv6/addrconf.c:-1
process_one_work+0x6c8/0xbb0 kernel/workqueue.c:2328
worker_thread+0xaa0/0x1250 kernel/workqueue.c:2475
kthread+0x3f5/0x4f0 kernel/kthread.c:337
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Modules linked in:
---[ end trace f8214f4497f41bb9 ]---
RIP: 0010:dummy_queue+0x1b7/0x870 drivers/usb/gadget/udc/dummy_hcd.c:714
Code: fc ff df 80 3c 08 00 74 08 4c 89 e7 e8 12 56 7f fe 4d 8b 24 24 49 83 c4 48 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 80 05 00 00 45 8b 24 24 44 89 e6 83 e6 02
RSP: 0018:ffffc90000f97000 EFLAGS: 00010206
RAX: 0000000000000009 RBX: ffff888133872310 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000005
RBP: ffffc90000f97078 R08: ffff88810dc486a3 R09: 1ffff11021b890d4
R10: dffffc0000000000 R11: ffffed1021b890d5 R12: 0000000000000048
R13: ffff888133872300 R14: 1ffff1102670e460 R15: ffff88810b70cc90
FS: 0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2eae12 CR3: 00000001266e5000 CR4: 00000000003506b0
----------------
Code disassembly (best guess):
0: fc cld
1: ff lcall (bad)
2: df 80 3c 08 00 74 filds 0x7400083c(%rax)
8: 08 4c 89 e7 or %cl,-0x19(%rcx,%rcx,4)
c: e8 12 56 7f fe call 0xfe7f5623
11: 4d 8b 24 24 mov (%r12),%r12
15: 49 83 c4 48 add $0x48,%r12
19: 4c 89 e0 mov %r12,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 0f b6 04 08 movzbl (%rax,%rcx,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 0f 85 80 05 00 00 jne 0x5b6
36: 45 8b 24 24 mov (%r12),%r12d
3a: 44 89 e6 mov %r12d,%esi
3d: 83 e6 02 and $0x2,%esi
* Struck through repros no longer work on HEAD.