KASAN: use-after-free Read in __dynamic_dev_dbg

Status: upstream: reported on 2026/10/17 04:30
Reported-by: syzbot+22dc29a0302bd303378c@syzkaller.appspotmail.com
First crash: 18d, last: 6h57m
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: slab-out-of-bounds Read in __dynamic_dev_dbg origin:upstream 19 syz, C 7 34d 47d 0/3 upstream: reported C repro on 2026/09/18 17:57
linux-6.6 general protection fault in __dynamic_dev_dbg 2 1 45d 45d 0/2 upstream: reported on 2026/09/21 02:53
upstream KASAN: slab-use-after-free Read in __dynamic_dev_dbg prio:normal driver-core media 19 syz, C 560 4h12m 49d 26/29 upstream: reported C repro on 2026/09/16 15:53

Sample crash report:
usb 5-1: selecting invalid altsetting 0
usb 5-1: 0:0: usb_set_interface failed (-22)
==================================================================
BUG: KASAN: use-after-free in dev_driver_string+0x31/0xc0 drivers/base/core.c:2095
Read of size 8 at addr ffff888079ba2098 by task syz.4.1861/12086

CPU: 0 PID: 12086 Comm: syz.4.1861 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 dev_driver_string+0x31/0xc0 drivers/base/core.c:2095
 __dynamic_dev_dbg+0x19d/0x2b0 lib/dynamic_debug.c:646
 snd_pcm_oss_change_params_locked+0x3bb5/0x3cf0 sound/core/oss/pcm_oss.c:-1
 snd_pcm_oss_make_ready_locked sound/core/oss/pcm_oss.c:1191 [inline]
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1409 [inline]
 snd_pcm_oss_write+0x26d/0xb10 sound/core/oss/pcm_oss.c:2810
 vfs_write+0x304/0xd70 fs/read_write.c:592
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1405eadb19
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:00007f1404104028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1406133fa0 RCX: 00007f1405eadb19
RDX: 0000000000000015 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f1405f45b70 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1406134038 R14: 00007f1406133fa0 R15: 00007ffef0a2be18
 </TASK>

Allocated by task 7:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xaf/0xe0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:607 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 usb_set_configuration+0x3b6/0x2140 drivers/usb/core/message.c:2057
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x126/0x250 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x276/0xc70 drivers/base/dd.c:595
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:775
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:805
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:927
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a7/0x480 drivers/base/dd.c:999
 bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
 device_add+0xbcf/0x1050 drivers/base/core.c:3427
 usb_new_device+0x9f6/0x15d0 drivers/usb/core/hub.c:2642
 hub_port_connect drivers/usb/core/hub.c:5507 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5647 [inline]
 port_event drivers/usb/core/hub.c:5809 [inline]
 hub_event+0x2b8d/0x5260 drivers/usb/core/hub.c:5891
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Freed by task 4730:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 device_release+0x92/0x1c0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:713 [inline]
 kobject_release lib/kobject.c:744 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x217/0x450 lib/kobject.c:761
 usb_disable_device+0x612/0x8a0 drivers/usb/core/message.c:1485
 usb_disconnect+0x33c/0x8a0 drivers/usb/core/hub.c:2297
 hub_port_connect drivers/usb/core/hub.c:5351 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5647 [inline]
 port_event drivers/usb/core/hub.c:5809 [inline]
 hub_event+0x1d64/0x5260 drivers/usb/core/hub.c:5891
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 kvfree_call_rcu+0x105/0x7f0 kernel/rcu/tree.c:3600
 drop_sysctl_table+0x359/0x4e0 fs/proc/proc_sysctl.c:1685
 unregister_sysctl_table+0x87/0x130 fs/proc/proc_sysctl.c:1723
 __addrconf_sysctl_unregister net/ipv6/addrconf.c:7158 [inline]
 addrconf_sysctl_unregister net/ipv6/addrconf.c:7186 [inline]
 addrconf_ifdown+0x1671/0x19f0 net/ipv6/addrconf.c:3946
 addrconf_notify+0x445/0xf20 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2074 [inline]
 call_netdevice_notifiers net/core/dev.c:2088 [inline]
 unregister_netdevice_many+0x109b/0x1a40 net/core/dev.c:11161
 ieee80211_remove_interfaces+0x44b/0x700 net/mac80211/iface.c:2168
 ieee80211_unregister_hw+0x55/0x220 net/mac80211/main.c:1400
 mac80211_hwsim_del_radio+0x282/0x470 drivers/net/wireless/mac80211_hwsim.c:3472
 hwsim_exit_net+0x589/0x650 drivers/net/wireless/mac80211_hwsim.c:4242
 ops_exit_list net/core/net_namespace.c:172 [inline]
 cleanup_net+0x703/0xba0 net/core/net_namespace.c:635
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Second to last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 __call_rcu kernel/rcu/tree.c:3011 [inline]
 call_rcu+0x189/0x900 kernel/rcu/tree.c:3091
 in6_dev_put include/net/addrconf.h:389 [inline]
 addrconf_ifdown+0x1778/0x19f0 net/ipv6/addrconf.c:3949
 addrconf_notify+0x445/0xf20 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2074 [inline]
 call_netdevice_notifiers net/core/dev.c:2088 [inline]
 unregister_netdevice_many+0x109b/0x1a40 net/core/dev.c:11161
 __rtnl_newlink net/core/rtnetlink.c:3569 [inline]
 rtnl_newlink+0x1779/0x1920 net/core/rtnetlink.c:3586
 rtnetlink_rcv_msg+0x7f1/0xf10 net/core/rtnetlink.c:5698
 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2527
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x804/0x9e0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1927
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446
 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500
 __sys_sendmsg net/socket.c:2529 [inline]
 __do_sys_sendmsg net/socket.c:2538 [inline]
 __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888079ba2000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 152 bytes inside of
 2048-byte region [ffff888079ba2000, ffff888079ba2800)
The buggy address belongs to the page:
page:ffffea0001e6e800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x79ba0
head:ffffea0001e6e800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888017842000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4191, ts 62487938052, free_ts 62483041170
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 __kmalloc_track_caller+0x11b/0x330 mm/slub.c:4930
 kmemdup+0x22/0x50 mm/util.c:128
 neigh_sysctl_register+0xab/0xa90 net/core/neighbour.c:3652
 addrconf_sysctl_register+0xac/0x1b0 net/ipv6/addrconf.c:7172
 ipv6_add_dev+0xbfb/0x11a0 net/ipv6/addrconf.c:454
 addrconf_notify+0x66f/0xf20 net/ipv6/addrconf.c:3594
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 call_netdevice_notifiers_extack net/core/dev.c:2074 [inline]
 call_netdevice_notifiers net/core/dev.c:2088 [inline]
 register_netdevice+0x12a8/0x1720 net/core/dev.c:10455
 __ip_tunnel_create+0x2c7/0x390 net/ipv4/ip_tunnel.c:267
 ip_tunnel_init_net+0x246/0x710 net/ipv4/ip_tunnel.c:1084
 ops_init+0x360/0x5f0 net/core/net_namespace.c:138
 setup_net+0x39e/0xa10 net/core/net_namespace.c:333
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
 kmem_cache_zalloc include/linux/slab.h:728 [inline]
 __kernfs_new_node+0xe3/0x6b0 fs/kernfs/dir.c:593
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
 __kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:985
 sysfs_add_file_mode_ns+0x2d2/0x390 fs/sysfs/file.c:321
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x492/0xd00 fs/sysfs/group.c:149
 netdev_queue_add_kobject net/core/net-sysfs.c:1672 [inline]
 netdev_queue_update_kobjects+0x1bc/0x3e0 net/core/net-sysfs.c:1711
 register_queue_kobjects net/core/net-sysfs.c:1772 [inline]
 netdev_register_kobject+0x273/0x320 net/core/net-sysfs.c:2018
 register_netdevice+0x10e8/0x1720 net/core/dev.c:10424
 __ip_tunnel_create+0x2c7/0x390 net/ipv4/ip_tunnel.c:267

Memory state around the buggy address:
 ffff888079ba1f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888079ba2000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888079ba2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888079ba2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888079ba2180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/04 20:08 linux-5.15.y 700e62ea909a 73438ed0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in __dynamic_dev_dbg
2026/10/26 16:05 linux-5.15.y 792fbe1537d8 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in __dynamic_dev_dbg
2026/10/20 15:59 linux-5.15.y 792fbe1537d8 df8746fb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in __dynamic_dev_dbg
2026/10/20 15:59 linux-5.15.y 792fbe1537d8 df8746fb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in __dynamic_dev_dbg
2026/10/17 04:29 linux-5.15.y 792fbe1537d8 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in __dynamic_dev_dbg
* Struck through repros no longer work on HEAD.