| 0/0 |
2026/03/08 07:45 |
flow |
repro |
9m
Results: map[ReproOpts:{
"progs": [
"r1 = socket$inet6(0xa, 0x2, 0x0)\nr0 = socket$netlink(0x10, 0x3, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000000)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"bridge0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"bridge\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000100)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"dummy0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"dummy\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000200)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x0, 0x0, 0x0}, [{@master={0x0, 0xa, 0x2}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000300)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x2, 0x1, 0x1, 0x0}, []}, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000400)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x1, 0x1, 0x0}, []}, 0x0)"
]
} ReproSyz:r1 = socket$inet6(0xa, 0x2, 0x0)
r0 = socket$netlink(0x10, 0x3, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000000)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, "bridge0\x00"}, @info={0x0, 0x12, {@kind={0x0, 0x1, "bridge\x00"}}}}] }, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000100)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, "dummy0\x00"}, @info={0x0, 0x12, {@kind={0x0, 0x1, "dummy\x00"}}}}] }, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000200)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x0, 0x0, 0x0}, [{@master={0x0, 0xa, 0x2}}] }, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000300)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x2, 0x1, 0x1, 0x0}, []}, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000400)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x1, 0x1, 0x0}, []}, 0x0)
SyzkallerCommit:31e9c887f7dc24e04b3ca70d0d54fc34141844b0]
|
| 1/1 |
2026/03/08 07:45 |
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 |
2026/03/08 07:45 |
action |
kernel-checkouter |
0m
Results: map[KernelSrc:/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/src/8518f00081054eb4f17482a283c0b801ddfbf6eb]
|
| 3/1 |
2026/03/08 07:46 |
action |
kernel-builder |
5m
Results: map[KernelObj:/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/00f4d0ee82ce6a2b20bab0c44f8dd3e552e116b5]
|
| 4/1 |
2026/03/08 07:52 |
agent |
crash-repro-finder |
2m
Model:
Results: map[ReproOpts:{
"progs": [
"r1 = socket$inet6(0xa, 0x2, 0x0)\nr0 = socket$netlink(0x10, 0x3, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000000)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"bridge0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"bridge\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000100)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"dummy0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"dummy\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000200)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x0, 0x0, 0x0}, [{@master={0x0, 0xa, 0x2}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000300)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x2, 0x1, 0x1, 0x0}, []}, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000400)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x1, 0x1, 0x0}, []}, 0x0)"
]
}]
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 Write in rt6_disable_ip
Original Crash Report:
bridge0: port 2(bridge_slave_1) entered disabled state
bridge_slave_0: left allmulticast mode
bridge_slave_0: left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
==================================================================
BUG: KASAN: slab-use-after-free in INIT_LIST_HEAD include/linux/list.h:46 [inline]
BUG: KASAN: slab-use-after-free in list_del_init include/linux/list.h:296 [inline]
BUG: KASAN: slab-use-after-free in rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]
BUG: KASAN: slab-use-after-free in rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020
Write of size 8 at addr ffff8880294cfa78 by task kworker/u8:14/3450
CPU: 0 UID: 0 PID: 3450 Comm: kworker/u8:14 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
Workqueue: netns cleanup_net
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
INIT_LIST_HEAD include/linux/list.h:46 [inline]
list_del_init include/linux/list.h:296 [inline]
rt6_uncached_list_flush_dev net/ipv6/route.c:191 [inline]
rt6_disable_ip+0x633/0x730 net/ipv6/route.c:5020
addrconf_ifdown+0x143/0x18a0 net/ipv6/addrconf.c:3853
addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1
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]
netif_close_many+0x29c/0x410 net/core/dev.c:1785
unregister_netdevice_many_notify+0xb50/0x2330 net/core/dev.c:12353
ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
ops_undo_list+0x3dc/0x990 net/core/net_namespace.c:248
cleanup_net+0x4de/0x7b0 net/core/net_namespace.c:696
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
</TASK>
Allocated by task 803:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270
dst_alloc+0x105/0x170 net/core/dst.c:89
ip6_dst_alloc net/ipv6/route.c:342 [inline]
icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333
mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844
mld_send_cr net/ipv6/mcast.c:2154 [inline]
mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693
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 20:
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]
kmem_cache_free+0x18f/0x8d0 mm/slub.c:6781
dst_destroy+0x235/0x350 net/core/dst.c:121
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core kernel/rcu/tree.c:2857 [inline]
rcu_cpu_kthread+0xba5/0x1af0 kernel/rcu/tree.c:2945
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
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
Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
__call_rcu_common kernel/rcu/tree.c:3119 [inline]
call_rcu+0xee/0x890 kernel/rcu/tree.c:3239
refdst_drop include/net/dst.h:266 [inline]
skb_dst_drop include/net/dst.h:278 [inline]
skb_release_head_state+0x71/0x360 net/core/skbuff.c:1156
skb_release_all net/core/skbuff.c:1180 [inline]
__kfree_skb net/core/skbuff.c:1196 [inline]
sk_skb_reason_drop+0xe9/0x170 net/core/skbuff.c:1234
kfree_skb_reason include/linux/skbuff.h:1322 [inline]
tcf_kfree_skb_list include/net/sch_generic.h:1127 [inline]
__dev_xmit_skb net/core/dev.c:4260 [inline]
__dev_queue_xmit+0x26aa/0x3210 net/core/dev.c:4785
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247
NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318
mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855
mld_send_cr net/ipv6/mcast.c:2154 [inline]
mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693
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
The buggy address belongs to the object at ffff8880294cfa00
which belongs to the cache ip6_dst_cache of size 232
The buggy address is located 120 bytes inside of
freed 232-byte region [ffff8880294cfa00, ffff8880294cfae8)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x294cf
memcg:ffff88803536b781
flags: 0x80000000000000(node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000000 ffff88802ff1c8c0 ffffea0000bf2bc0 dead000000000006
raw: 0000000000000000 00000000800c000c 00000000f5000000 ffff88803536b781
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 9, tgid 9 (kworker/0:0), ts 91119585830, free_ts 91088628818
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]
kmem_cache_alloc_noprof+0x101/0x6c0 mm/slub.c:5270
dst_alloc+0x105/0x170 net/core/dst.c:89
ip6_dst_alloc net/ipv6/route.c:342 [inline]
icmp6_dst_alloc+0x75/0x460 net/ipv6/route.c:3333
mld_sendpack+0x683/0xe60 net/ipv6/mcast.c:1844
mld_send_cr net/ipv6/mcast.c:2154 [inline]
mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693
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
page last free pid 5859 tgid 5859 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xfe1/0x1170 mm/page_alloc.c:2943
discard_slab mm/slub.c:3346 [inline]
__put_partials+0x149/0x170 mm/slub.c:3886
__slab_free+0x2af/0x330 mm/slub.c:5952
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_noprof+0x18d/0x6c0 mm/slub.c:5270
getname_flags+0xb8/0x540 fs/namei.c:146
getname include/linux/fs.h:2498 [inline]
do_sys_openat2+0xbc/0x200 fs/open.c:1426
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1447
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff8880294cf900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880294cf980: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff8880294cfa00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880294cfa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff8880294cfb00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================
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: r1 = socket$inet6(0xa, 0x2, 0x0)
r0 = socket$netlink(0x10, 0x3, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000000)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, "bridge0\x00"}, @info={0x0, 0x12, {@kind={0x0, 0x1, "bridge\x00"}}}}] }, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000100)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, "dummy0\x00"}, @info={0x0, 0x12, {@kind={0x0, 0x1, "dummy\x00"}}}}] }, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000200)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x0, 0x0, 0x0}, [{@master={0x0, 0xa, 0x2}}] }, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000300)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x2, 0x1, 0x1, 0x0}, []}, 0x0)
sendmsg$RTM_NEWLINK(r0, &(0x7f0000000400)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x1, 0x1, 0x0}, []}, 0x0)
|
| 5/2 |
2026/03/08 07:52 |
llm |
crash-repro-finder |
2m
Model:
Tokens:
input: 6558
output: 667
thoughts: 19612
Thoughts: **KASAN UAF in rt6_disable_ip: A Detailed Breakdown**
Okay, so I'm digging into this KASAN: slab-use-after-free bug. The crash report's pointing to a write of size 8 at an `ip6_dst_cache` address, triggered by `rt6_disable_ip`. This thing's happening during a network namespace or device teardown, and it seems like an `rt6_info` (or something similar in `ip6_dst_cache`) is getting accessed *after* it's been freed.
The crash chain traces through `rt6_disable_ip` calling `rt6_uncached_list_flush_dev`, which then uses `list_del_init`. The allocation path involves `mld_sendpack`, `icmp6_dst_alloc`, indicating multicast listener discovery for IPv6 is in play. The freeing stack shows the object being destroyed through RCU (`dst_destroy` -> `kmem_cache_free`). It appears this `dst_entry` ended up on an uncached list, likely tied to a network device going down.
It appears the kernel is attempting to flush the uncached list for the device, which is an `rt6_info` structure that was associated with the device, but not in the main routing table. These entries are created for ICMP redirects, or MLD traffic. This `mld_sendpack` allocating `dst` explains that and is likely a MLD packet. So, a device on a bridge is being taken down, and the kernel is trying to clean up its routing information at the same time.
It looks like the sequence of events is: create a netns, set up a bridge, add some interfaces to the bridge, enable IPv6, trigger some MLD traffic, which then allocates the `ip6_dst_cache` objects, adds them to an uncached list on the device, destroy the namespace or the bridge and then `rt6_disable_ip` tries to flush the list, hitting a use-after-free because an entry was freed by RCU. The bridge setup involves `bridge0` and `bridge_slave_0`/`1`, suggesting namespace cleanup with bridge device destruction.
The repro should create a new netns, make a bridge, add interfaces (dummy or veth), generate MLD traffic (interfaces up, or with injected MLD packets), and then exit the namespace or the process to trigger the `cleanup_net`. This creates a race condition.
Iβm seeing that `mld_sendpack` uses `icmp6_dst_alloc` to allocate the destination, setting `dst->dev`, and that `dst` is freed by `dst_destroy` (via RCU). The key is the interaction between `rt6_uncached_list_flush_dev` which iterates and attempts to delete from a list and `dst_destroy` which attempts to remove it and then free it. These two are synchronized by a lock.
I need to understand if there's a race between `dst_destroy` (RCU callback, frees) and `rt6_disable_ip` (cleanup, accesses). If they are serialized by a lock, how can there be UAF? It's the list iteration combined with freeing in parallel. It is a race between two threads modifying and traversing the same list of destinations that were allocated for multicast.
The current code that is crashing, in particular the `rt6_uncached_list_flush_dev` does not take the device out of the list. Instead it sets the device to the loopback, which is a known bug. But the bug exists in prior kernel versions.
I'm checking the lock handling. I see that `rt6_uncached_list_del` takes a lock to remove the entry, so I'm thinking about concurrent calls to this, or if the lock is dropped. I'm investigating what happens if `rt6_uncached_list_flush_dev` iterates through the list, picks an entry, then, *concurrently* that entry gets destroyed, removed from the list, and freed. It appears the old list entry pointer is still cached in `next` in the current iteration and the object gets accessed after itβs freed (UAF). The object being accessed is on a list. The code does `list_for_each_entry_safe` which saves the `next` pointer before doing work. If `next` is freed before the current list entry pointer, we get UAF on the `next` pointer.
So here's what I think: The syzkaller program will be building a bridge, adding a veth pair to that bridge, and then bringing up these network devices. Then the netns will be destroyed which will initiate the destruction of the bridge
|
| 6/2 |
2026/03/08 07:54 |
tool |
set-results |
0m
Args: map[ReproOpts:{
"progs": [
"r1 = socket$inet6(0xa, 0x2, 0x0)\nr0 = socket$netlink(0x10, 0x3, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000000)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"bridge0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"bridge\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000100)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"dummy0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"dummy\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000200)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x0, 0x0, 0x0}, [{@master={0x0, 0xa, 0x2}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000300)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x2, 0x1, 0x1, 0x0}, []}, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000400)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x1, 0x1, 0x0}, []}, 0x0)"
]
}]
Results: map[ReproOpts:{
"progs": [
"r1 = socket$inet6(0xa, 0x2, 0x0)\nr0 = socket$netlink(0x10, 0x3, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000000)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"bridge0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"bridge\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000100)={{0x0, 0x10, 0x601, 0x0, 0x0}, {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, [{@name={0x0, 0x3, \"dummy0\\x00\"}, @info={0x0, 0x12, {@kind={0x0, 0x1, \"dummy\\x00\"}}}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000200)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x0, 0x0, 0x0}, [{@master={0x0, 0xa, 0x2}}] }, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000300)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x2, 0x1, 0x1, 0x0}, []}, 0x0)\nsendmsg$RTM_NEWLINK(r0, &(0x7f0000000400)={{0x0, 0x10, 0x1, 0x0, 0x0}, {0x0, 0x0, 0x3, 0x1, 0x1, 0x0}, []}, 0x0)"
]
}]
|
| 7/2 |
2026/03/08 07:54 |
llm |
crash-repro-finder |
0m
Model:
Tokens:
input: 28527
output: 632
thoughts: 0
|