| 0/0 |
2026/03/06 21:56 |
flow |
repro |
10m
Results: map[ReproOpts:{
"threaded": true,
"repeat": true,
"procs": 1,
"sandbox": "none",
"fault_call": -1
} ReproSyz:r0 = socket(0x2, 0x1, 0x0)
setsockopt(r0, 0x1, 0x2, &(0x7f000000)=0x1, 0x4)
bind(r0, &(0x7f000000)={0x2, 0x4e20, 0x100007f}, 0x10)
listen(r0, 0x1)
r1 = socket(0x2, 0x1, 0x0)
connect(r1, &(0x7f000000)={0x2, 0x4e20, 0x100007f}, 0x10)
r2 = accept(r0, 0x0, 0x0)
setsockopt(r2, 0x6, 0x1, &(0x7f000000)=0x1, 0x4)
write(r2, &(0x7f000000)=@pdu={0x3000000, 0x1000000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x3000000, 0x1000000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
r3 = openat(0xffffffffffffff9c, &"/dev/vhci\x00", 0x2, 0x0)
ioctl(r3, 0x40101b01, &(0x7f000000)={0x0, r1, 0x0, 0x3})
SyzkallerCommit:31e9c887f7dc24e04b3ca70d0d54fc34141844b0]
|
| 1/1 |
2026/03/06 21:56 |
action |
provide-var |
0m
Results: map[DescriptionFiles:[acpi_thermal_rel.txt aio.txt auto.txt binfmt.txt bpf.txt bpf_prog.txt bpf_trace.txt cgroup.txt damon.txt dev_ashmem.txt dev_bifrost.txt dev_binder.txt dev_binderfs.txt dev_block.txt dev_bsg.txt dev_bus_usb.txt dev_camx.txt dev_cdrom.txt dev_cec.txt dev_char_usb.txt dev_comedi.txt dev_dma_heap.txt dev_dri.txt dev_dsp.txt dev_dvb_demux.txt dev_dvb_dvr.txt dev_dvb_frontend.txt dev_fb.txt dev_floppy.txt dev_hidraw.txt dev_i2c.txt dev_i915.txt dev_img_rogue.txt dev_infiniband_rdma.txt dev_infiniband_rdma_cm.txt dev_input.txt dev_iommu.txt dev_kvm.txt dev_kvm_amd64.txt dev_kvm_arm64.txt dev_kvm_extra.txt dev_kvm_riscv64.txt dev_loop.txt dev_mali.txt dev_media.txt dev_msm.txt dev_msr.txt dev_nbd.txt dev_net_tun.txt dev_panthor.txt dev_ppp.txt dev_ptmx.txt dev_ptp.txt dev_qat_adf_ctl.txt dev_qrtr_tun.txt dev_random.txt dev_rfkill.txt dev_rtc.txt dev_sequencer.txt dev_sg.txt dev_snapshot.txt dev_snd_control.txt dev_snd_hw.txt dev_snd_midi.txt dev_snd_pcm.txt dev_snd_seq.txt dev_snd_timer.txt dev_sr.txt dev_sw_sync.txt dev_tlk_device.txt dev_trusty.txt dev_udmabuf.txt dev_uhid.txt dev_uinput.txt dev_usb_hiddev.txt dev_usbmon.txt dev_userio.txt dev_vfio.txt dev_vga_arbiter.txt dev_vhci.txt dev_video4linux.txt dev_video4linux_vim2m.txt dev_virtual_nci.txt dev_vtpm.txt fanotify.txt filesystem.txt fs_9p.txt fs_fuse.txt fs_incfs.txt fs_ioctl.txt fs_ioctl_autofs.txt fs_ioctl_btrfs.txt fs_ioctl_ext4.txt fs_ioctl_f2fs.txt fs_ioctl_fat.txt fs_ioctl_fscrypt.txt fs_ioctl_fsverity.txt fs_ioctl_xfs.txt futex.txt hafnium.txt inotify.txt io_uring.txt ipc.txt key.txt kfuzztest.txt l2cap.txt landlock.txt lsm.txt namespaces.txt net_80211.txt netfilter.txt netfilter_arp.txt netfilter_bridge.txt netfilter_ipv4.txt netfilter_ipv6.txt netfilter_ipvs.txt netfilter_targets.txt pagemap_ioctl.txt perf.txt prctl.txt quotactl.txt seccomp.txt security_apparmor.txt security_selinux.txt security_smack.txt socket.txt socket_alg.txt socket_ax25.txt socket_bluetooth.txt socket_caif.txt socket_can.txt socket_ieee802154.txt socket_inet.txt socket_inet6.txt socket_inet_dccp.txt socket_inet_icmp.txt socket_inet_igmp.txt socket_inet_l2tp.txt socket_inet_sctp.txt socket_inet_tcp.txt socket_inet_udp.txt socket_ip_tunnel.txt socket_isdn.txt socket_kcm.txt socket_key.txt socket_llc.txt socket_netlink.txt socket_netlink_audit.txt socket_netlink_crypto.txt socket_netlink_generic.txt socket_netlink_generic_80211.txt socket_netlink_generic_batadv.txt socket_netlink_generic_devlink.txt socket_netlink_generic_ethtool.txt socket_netlink_generic_fou.txt socket_netlink_generic_gtp.txt socket_netlink_generic_mptcp.txt socket_netlink_generic_net_dm.txt socket_netlink_generic_netlabel.txt socket_netlink_generic_nfc.txt socket_netlink_generic_seg6.txt socket_netlink_generic_smc.txt socket_netlink_generic_team.txt socket_netlink_generic_wireguard.txt socket_netlink_netfilter.txt socket_netlink_netfilter_acct.txt socket_netlink_netfilter_conntrack.txt socket_netlink_netfilter_conntrack_exp.txt socket_netlink_netfilter_conntrack_helper.txt socket_netlink_netfilter_ipset.txt socket_netlink_netfilter_log.txt socket_netlink_netfilter_nft_compat.txt socket_netlink_netfilter_nftables.txt socket_netlink_netfilter_osf.txt socket_netlink_netfilter_queue.txt socket_netlink_netfilter_timeout.txt socket_netlink_rdma.txt socket_netlink_route.txt socket_netlink_route_sched.txt socket_netlink_route_sched_retired.txt socket_netlink_sock_diag.txt socket_netlink_xfrm.txt socket_netrom.txt socket_nfc.txt socket_nvme_of_tcp.txt socket_packet.txt socket_phonet.txt socket_pppox.txt socket_qipcrtr.txt socket_rds.txt socket_rose.txt socket_rxrpc.txt socket_tipc.txt socket_tipc_netlink.txt socket_unix.txt socket_vnet.txt socket_x25.txt socket_xdp.txt sys.txt uffd.txt usbip.txt vmw_vmci.txt vnet.txt vnet_mptcp.txt vusb.txt watch_queue.txt xattr.txt] SyzkallerCommit:31e9c887f7dc24e04b3ca70d0d54fc34141844b0]
|
| 2/1 |
2026/03/06 21:56 |
action |
kernel-checkouter |
0m
Results: map[KernelSrc:/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/src/8518f00081054eb4f17482a283c0b801ddfbf6eb]
|
| 3/1 |
2026/03/06 21:56 |
action |
kernel-builder |
5m
Results: map[KernelObj:/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/00f4d0ee82ce6a2b20bab0c44f8dd3e552e116b5]
|
| 4/1 |
2026/03/06 22:02 |
agent |
crash-repro-finder |
3m
Model:
Results: map[ReproOpts:{
"threaded": true,
"repeat": true,
"procs": 1,
"sandbox": "none",
"fault_call": -1
}]
Instruction:
You are an expert in linux kernel fuzzing. Your goal is to write a syzkaller program to trigger a specific bug.
Print only the syz program that could be executed directly, without backticks.
Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.
Prompt:
Bug Title: KASAN: slab-use-after-free Read in vhci_tx_loop
Original Crash Report:
==================================================================
BUG: KASAN: slab-use-after-free in vhci_send_cmd_submit drivers/usb/usbip/vhci_tx.c:69 [inline]
BUG: KASAN: slab-use-after-free in vhci_tx_loop+0x38e/0x1a80 drivers/usb/usbip/vhci_tx.c:241
Read of size 8 at addr ffff88805b8309a0 by task vhci_tx/30838
CPU: 1 UID: 0 PID: 30838 Comm: vhci_tx Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
vhci_send_cmd_submit drivers/usb/usbip/vhci_tx.c:69 [inline]
vhci_tx_loop+0x38e/0x1a80 drivers/usb/usbip/vhci_tx.c:241
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>
Allocated by task 9958:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x1fb/0x6d0 mm/slub.c:5776
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
vhci_tx_urb drivers/usb/usbip/vhci_hcd.c:674 [inline]
vhci_urb_enqueue+0x5cd/0xe30 drivers/usb/usbip/vhci_hcd.c:829
usb_hcd_submit_urb+0x323/0x1b60 drivers/usb/core/hcd.c:1546
usb_start_wait_urb+0x115/0x4f0 drivers/usb/core/message.c:59
usb_internal_control_msg drivers/usb/core/message.c:103 [inline]
usb_control_msg+0x232/0x3e0 drivers/usb/core/message.c:154
get_bMaxPacketSize0 drivers/usb/core/hub.c:4851 [inline]
hub_port_init+0xb1d/0x28d0 drivers/usb/core/hub.c:5047
hub_port_connect drivers/usb/core/hub.c:5496 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x25b3/0x4f30 drivers/usb/core/hub.c:5953
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Freed by task 30837:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6670 [inline]
kfree+0x1bd/0x900 mm/slub.c:6878
pickup_urb_and_free_priv+0x225/0x400 drivers/usb/usbip/vhci_rx.c:46
vhci_recv_ret_submit drivers/usb/usbip/vhci_rx.c:65 [inline]
vhci_rx_pdu drivers/usb/usbip/vhci_rx.c:242 [inline]
vhci_rx_loop+0x39f/0x9d0 drivers/usb/usbip/vhci_rx.c:265
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
The buggy address belongs to the object at ffff88805b830980
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 32 bytes inside of
freed 64-byte region [ffff88805b830980, ffff88805b8309c0)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5b830
flags: 0x80000000000000(node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000000 ffff88813ff268c0 ffffea0000c33bc0 dead000000000004
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5805, tgid 5805 (syz-executor), ts 102265955235, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
prep_new_page mm/page_alloc.c:1865 [inline]
get_page_from_freelist+0x28c0/0x2960 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3b0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xb10/0x13e0 mm/slub.c:4656
__slab_alloc+0xc6/0x1f0 mm/slub.c:4779
__slab_alloc_node mm/slub.c:4855 [inline]
slab_alloc_node mm/slub.c:5251 [inline]
__do_kmalloc_node mm/slub.c:5656 [inline]
__kmalloc_node_track_caller_noprof+0x2bf/0x810 mm/slub.c:5764
kmemdup_noprof+0x2b/0x70 mm/util.c:138
kmemdup_noprof include/linux/fortify-string.h:765 [inline]
mpls_dev_sysctl_register+0xbd/0x270 net/mpls/af_mpls.c:1422
mpls_add_dev net/mpls/af_mpls.c:1490 [inline]
mpls_dev_notify+0x394/0xd10 net/mpls/af_mpls.c:1635
notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
call_netdevice_notifiers net/core/dev.c:2282 [inline]
register_netdevice+0x15d2/0x1a80 net/core/dev.c:11431
register_netdev+0x40/0x60 net/core/dev.c:11509
vti6_init_net+0x238/0x370 net/ipv6/ip6_vti.c:1158
ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
page_owner free stack trace missing
Memory state around the buggy address:
ffff88805b830880: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
ffff88805b830900: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff88805b830980: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffff88805b830a00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88805b830a80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
==================================================================
The list of existing description files:
acpi_thermal_rel.txt
aio.txt
auto.txt
binfmt.txt
bpf.txt
bpf_prog.txt
bpf_trace.txt
cgroup.txt
damon.txt
dev_ashmem.txt
dev_bifrost.txt
dev_binder.txt
dev_binderfs.txt
dev_block.txt
dev_bsg.txt
dev_bus_usb.txt
dev_camx.txt
dev_cdrom.txt
dev_cec.txt
dev_char_usb.txt
dev_comedi.txt
dev_dma_heap.txt
dev_dri.txt
dev_dsp.txt
dev_dvb_demux.txt
dev_dvb_dvr.txt
dev_dvb_frontend.txt
dev_fb.txt
dev_floppy.txt
dev_hidraw.txt
dev_i2c.txt
dev_i915.txt
dev_img_rogue.txt
dev_infiniband_rdma.txt
dev_infiniband_rdma_cm.txt
dev_input.txt
dev_iommu.txt
dev_kvm.txt
dev_kvm_amd64.txt
dev_kvm_arm64.txt
dev_kvm_extra.txt
dev_kvm_riscv64.txt
dev_loop.txt
dev_mali.txt
dev_media.txt
dev_msm.txt
dev_msr.txt
dev_nbd.txt
dev_net_tun.txt
dev_panthor.txt
dev_ppp.txt
dev_ptmx.txt
dev_ptp.txt
dev_qat_adf_ctl.txt
dev_qrtr_tun.txt
dev_random.txt
dev_rfkill.txt
dev_rtc.txt
dev_sequencer.txt
dev_sg.txt
dev_snapshot.txt
dev_snd_control.txt
dev_snd_hw.txt
dev_snd_midi.txt
dev_snd_pcm.txt
dev_snd_seq.txt
dev_snd_timer.txt
dev_sr.txt
dev_sw_sync.txt
dev_tlk_device.txt
dev_trusty.txt
dev_udmabuf.txt
dev_uhid.txt
dev_uinput.txt
dev_usb_hiddev.txt
dev_usbmon.txt
dev_userio.txt
dev_vfio.txt
dev_vga_arbiter.txt
dev_vhci.txt
dev_video4linux.txt
dev_video4linux_vim2m.txt
dev_virtual_nci.txt
dev_vtpm.txt
fanotify.txt
filesystem.txt
fs_9p.txt
fs_fuse.txt
fs_incfs.txt
fs_ioctl.txt
fs_ioctl_autofs.txt
fs_ioctl_btrfs.txt
fs_ioctl_ext4.txt
fs_ioctl_f2fs.txt
fs_ioctl_fat.txt
fs_ioctl_fscrypt.txt
fs_ioctl_fsverity.txt
fs_ioctl_xfs.txt
futex.txt
hafnium.txt
inotify.txt
io_uring.txt
ipc.txt
key.txt
kfuzztest.txt
l2cap.txt
landlock.txt
lsm.txt
namespaces.txt
net_80211.txt
netfilter.txt
netfilter_arp.txt
netfilter_bridge.txt
netfilter_ipv4.txt
netfilter_ipv6.txt
netfilter_ipvs.txt
netfilter_targets.txt
pagemap_ioctl.txt
perf.txt
prctl.txt
quotactl.txt
seccomp.txt
security_apparmor.txt
security_selinux.txt
security_smack.txt
socket.txt
socket_alg.txt
socket_ax25.txt
socket_bluetooth.txt
socket_caif.txt
socket_can.txt
socket_ieee802154.txt
socket_inet.txt
socket_inet6.txt
socket_inet_dccp.txt
socket_inet_icmp.txt
socket_inet_igmp.txt
socket_inet_l2tp.txt
socket_inet_sctp.txt
socket_inet_tcp.txt
socket_inet_udp.txt
socket_ip_tunnel.txt
socket_isdn.txt
socket_kcm.txt
socket_key.txt
socket_llc.txt
socket_netlink.txt
socket_netlink_audit.txt
socket_netlink_crypto.txt
socket_netlink_generic.txt
socket_netlink_generic_80211.txt
socket_netlink_generic_batadv.txt
socket_netlink_generic_devlink.txt
socket_netlink_generic_ethtool.txt
socket_netlink_generic_fou.txt
socket_netlink_generic_gtp.txt
socket_netlink_generic_mptcp.txt
socket_netlink_generic_net_dm.txt
socket_netlink_generic_netlabel.txt
socket_netlink_generic_nfc.txt
socket_netlink_generic_seg6.txt
socket_netlink_generic_smc.txt
socket_netlink_generic_team.txt
socket_netlink_generic_wireguard.txt
socket_netlink_netfilter.txt
socket_netlink_netfilter_acct.txt
socket_netlink_netfilter_conntrack.txt
socket_netlink_netfilter_conntrack_exp.txt
socket_netlink_netfilter_conntrack_helper.txt
socket_netlink_netfilter_ipset.txt
socket_netlink_netfilter_log.txt
socket_netlink_netfilter_nft_compat.txt
socket_netlink_netfilter_nftables.txt
socket_netlink_netfilter_osf.txt
socket_netlink_netfilter_queue.txt
socket_netlink_netfilter_timeout.txt
socket_netlink_rdma.txt
socket_netlink_route.txt
socket_netlink_route_sched.txt
socket_netlink_route_sched_retired.txt
socket_netlink_sock_diag.txt
socket_netlink_xfrm.txt
socket_netrom.txt
socket_nfc.txt
socket_nvme_of_tcp.txt
socket_packet.txt
socket_phonet.txt
socket_pppox.txt
socket_qipcrtr.txt
socket_rds.txt
socket_rose.txt
socket_rxrpc.txt
socket_tipc.txt
socket_tipc_netlink.txt
socket_unix.txt
socket_vnet.txt
socket_x25.txt
socket_xdp.txt
sys.txt
uffd.txt
usbip.txt
vmw_vmci.txt
vnet.txt
vnet_mptcp.txt
vusb.txt
watch_queue.txt
xattr.txt
Reply: r0 = socket(0x2, 0x1, 0x0)
setsockopt(r0, 0x1, 0x2, &(0x7f000000)=0x1, 0x4)
bind(r0, &(0x7f000000)={0x2, 0x4e20, 0x100007f}, 0x10)
listen(r0, 0x1)
r1 = socket(0x2, 0x1, 0x0)
connect(r1, &(0x7f000000)={0x2, 0x4e20, 0x100007f}, 0x10)
r2 = accept(r0, 0x0, 0x0)
setsockopt(r2, 0x6, 0x1, &(0x7f000000)=0x1, 0x4)
write(r2, &(0x7f000000)=@pdu={0x3000000, 0x1000000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x3000000, 0x1000000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
write(r2, &(0x7f000000)=@pdu, 0x50)
r3 = openat(0xffffffffffffff9c, &"/dev/vhci\x00", 0x2, 0x0)
ioctl(r3, 0x40101b01, &(0x7f000000)={0x0, r1, 0x0, 0x3})
|
| 5/2 |
2026/03/06 22:02 |
llm |
crash-repro-finder |
3m
Model:
Tokens:
input: 4921
output: 60
thoughts: 19452
Thoughts: **VHCI USBIP UAF Bug Analysis and Syzkaller Reproduction**
Okay, here's the deal: I'm after a slab-use-after-free (UAF) in the `vhci` driver, specifically within the `vhci_tx_loop` function. The crash report pinpoints the bug in `drivers/usb/usbip/vhci_tx.c`. Essentially, the function `vhci_tx_loop` calls `vhci_send_cmd_submit`, which then tries to access memory that has already been freed. This freed memory originated from an object allocated through `vhci_tx_urb` -> `vhci_urb_enqueue` -> `usb_hcd_submit_urb`. The freeing occurs in a reverse path: `pickup_urb_and_free_priv` -> `vhci_recv_ret_submit` -> `vhci_rx_loop`.
This screams race condition. My theory is that the `vhci_tx` thread (responsible for sending commands for URBs) is trying to send a `CMD_SUBMIT` command for a URB, but the URB's private data (or the URB itself) has been freed by the `vhci_rx` thread (which handles return PDUs).
The `vhci` driver is for virtual USB host controllers, allowing USB devices to be connected over a network (USBIP). To trigger this, I suspect the following steps:
1. Open a VHCI controller.
2. Attach a virtual device (or simulate one).
3. Submit URBs to the device.
4. Concurrently, receive PDUs that complete or unlink these URBs.
The crash occurs in `vhci_tx_loop`, which is a kernel thread running when a connection is established for a port. The `vhci_rx_loop` also runs concurrently for the same connection.
The allocation stack trace suggests `vhci_tx_urb` allocates memory via `kzalloc`, likely a `struct vhci_priv` or similar, which keeps track of the URB. This allocation happens when a URB is submitted to the VHCI HCD. The size of the allocation, 64 bytes, seems to correspond with `sizeof(struct vhci_priv)`.
The freeing happens in `pickup_urb_and_free_priv`, which is called from `vhci_recv_ret_submit`.
The crash occurs in `vhci_send_cmd_submit`, where it accesses a `priv` variable retrieved from a list (`vdev->priv_tx`). It seems that `vhci_tx_loop` selects the `priv` from the `priv_tx` list to send over the socket, while `vhci_rx_loop` receives a RET\_SUBMIT packet corresponding to a URB, finds the `priv`, and frees it.
However, if `priv` is in the `priv_tx` list, it hasn't been sent yet. Why would `vhci_rx` receive a `RET_SUBMIT` for it? Unless unlinking or sequence number confusion is involved.
The `vhci` driver relies on TCP sockets for communication. I need to interact with the `vhci` driver. From available documentation (`dev_vhci.txt` and `usbip.txt`), `/dev/vhci` is likely the key. I need to open `/dev/vhci`, create a socket pair, attach a device to a port using the `USBIP_VHCI_ATTACH` ioctl on `/dev/vhci`, which takes the socket file descriptor. Then the kernel starts the `vhci_tx` and `vhci_rx` threads. The `vhci_tx` thread pulls URBs submitted by the USB core and sends them over the socket, while the `vhci_rx` thread reads from the socket and completes URBs.
To trigger the bug, I need to:
1. Attach a device.
2. Trigger a URB submission (which puts a `priv` in `priv_tx`).
3. `vhci_tx` thread wakes up to send it.
4. Concurrently, write to the socket (that `vhci_rx` reads), by sending a packet that causes `vhci_rx` to free the `priv` that `vhci_tx` is about to access.
The crucial part: `vhci_tx` picks `priv` from `priv_tx`, sends it, and then moves it to `priv_rx` (waiting for a reply). If `vhci_tx` is running `vhci_send_cmd_submit` and accesses `priv`, and if `vhci_rx` frees `priv`, then `priv` must be accessible
|
| 6/2 |
2026/03/06 22:06 |
tool |
set-results |
0m
Args: map[ReproOpts:{
"threaded": true,
"repeat": true,
"procs": 1,
"sandbox": "none",
"fault_call": -1
}]
Results: map[ReproOpts:{
"threaded": true,
"repeat": true,
"procs": 1,
"sandbox": "none",
"fault_call": -1
}]
|
| 7/2 |
2026/03/06 22:06 |
llm |
crash-repro-finder |
0m
Model:
Tokens:
input: 25516
output: 1011
thoughts: 0
|