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: 16d, last: 7d11h
▶ ▼ 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 32d 45d 0/3 upstream: reported C repro on 2026/09/18 17:57
linux-6.6 general protection fault in __dynamic_dev_dbg 2 1 43d 43d 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 553 2d02h 47d 26/29 upstream: reported C repro on 2026/09/16 15:53

Sample crash report:
usb 4-1: 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 ffff888075dfc098 by task syz.3.1299/11070

CPU: 0 PID: 11070 Comm: syz.3.1299 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_prepare sound/core/oss/pcm_oss.c:1149 [inline]
 snd_pcm_oss_make_ready_locked sound/core/oss/pcm_oss.c:1196 [inline]
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1409 [inline]
 snd_pcm_oss_write+0xb05/0xb10 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: 0033:0x7fc6878f8559
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:00007fc685b4f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc687b7efa0 RCX: 00007fc6878f8559
RDX: 0000000000000015 RSI: 0000200000000340 RDI: 0000000000000007
RBP: 00007fc68798fb20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc687b7f038 R14: 00007fc687b7efa0 R15: 00007ffd82209518
 </TASK>

Allocated by task 2305:
 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+0x3b6/0x2030 drivers/usb/core/message.c:2051
 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:2637
 hub_port_connect drivers/usb/core/hub.c:5502 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5642 [inline]
 port_event drivers/usb/core/hub.c:5804 [inline]
 hub_event+0x2b8d/0x5260 drivers/usb/core/hub.c:5886
 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 7628:
 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:1479
 usb_disconnect+0x33c/0x8a0 drivers/usb/core/hub.c:2292
 hub_port_connect drivers/usb/core/hub.c:5346 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5642 [inline]
 port_event drivers/usb/core/hub.c:5804 [inline]
 hub_event+0x1d64/0x5260 drivers/usb/core/hub.c:5886
 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
 default_device_exit_batch+0x364/0x3c0 net/core/dev.c:11694
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x78e/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

The buggy address belongs to the object at ffff888075dfc000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 152 bytes inside of
 2048-byte region [ffff888075dfc000, ffff888075dfc800)
The buggy address belongs to the page:
page:ffffea0001d77e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x75df8
head:ffffea0001d77e00 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 6824, ts 176002775149, free_ts 175978265376
 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
 devinet_sysctl_register+0xa8/0x1f0 net/ipv4/devinet.c:2640
 inetdev_init+0x28c/0x4d0 net/ipv4/devinet.c:277
 inetdev_event+0x26f/0x1350 net/ipv4/devinet.c:1543
 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
 veth_newlink+0x8ca/0xe20 drivers/net/veth.c:1718
 __rtnl_newlink net/core/rtnetlink.c:3538 [inline]
 rtnl_newlink+0x139e/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:2519
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
 free_slab mm/slub.c:2020 [inline]
 discard_slab mm/slub.c:2026 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2512
 put_cpu_partial+0x12d/0x190 mm/slub.c:2592
 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_trace+0x165/0x290 mm/slub.c:3250
 kmalloc include/linux/slab.h:607 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 kset_create lib/kobject.c:982 [inline]
 kset_create_and_add+0x56/0x160 lib/kobject.c:1025
 register_queue_kobjects net/core/net-sysfs.c:1759 [inline]
 netdev_register_kobject+0x1ae/0x320 net/core/net-sysfs.c:2018
 register_netdevice+0x10e8/0x1720 net/core/dev.c:10424
 register_netdev+0x37/0x50 net/core/dev.c:10548
 ip6gre_init_net+0x21f/0x2f0 net/ipv6/ip6_gre.c:1613
 ops_init+0x360/0x5f0 net/core/net_namespace.c:138
 setup_net+0x39e/0xa10 net/core/net_namespace.c:333

Memory state around the buggy address:
 ffff888075dfbf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888075dfc000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888075dfc080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888075dfc100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888075dfc180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.