syzbot


KASAN: slab-use-after-free Write in iowarrior_write_callback (2)

Status: moderation: reported on 2026/05/11 23:58
Subsystems: usb
[Documentation on labels]
Reported-by: syzbot+46d68e4d3bb12e604874@syzkaller.appspotmail.com
First crash: 4d21h, last: 4d21h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Write in iowarrior_write_callback usb 22 1 335d 331d 0/29 auto-obsoleted due to no activity on 2025/09/09 03:33

Sample crash report:
iowarrior 10-1:0.186: iowarrior_callback - usb_submit_urb failed with result -1
==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 [inline]
BUG: KASAN: slab-use-after-free in atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
BUG: KASAN: slab-use-after-free in iowarrior_write_callback+0xdc/0x190 drivers/usb/misc/iowarrior.c:236
Write of size 4 at addr ffff888050f49168 by task kworker/u32:13/17990

CPU: 0 UID: 0 PID: 17990 Comm: kworker/u32:13 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1d0 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:186 [inline]
 kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200
 instrument_atomic_read_write include/linux/instrumented.h:112 [inline]
 atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
 iowarrior_write_callback+0xdc/0x190 drivers/usb/misc/iowarrior.c:236
 __usb_hcd_giveback_urb+0x38d/0x610 drivers/usb/core/hcd.c:1657
 usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741
 dummy_timer+0xda1/0x36c0 drivers/usb/gadget/udc/dummy_hcd.c:2005
 __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
 __hrtimer_run_queues+0x470/0xa00 kernel/time/hrtimer.c:1994
 hrtimer_run_softirq+0x17d/0x2c0 kernel/time/hrtimer.c:2011
 handle_softirqs+0x1ea/0xa00 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:stackdepot_memcmp lib/stackdepot.c:585 [inline]
RIP: 0010:find_stack lib/stackdepot.c:618 [inline]
RIP: 0010:stack_depot_save_flags+0x1b5/0x9d0 lib/stackdepot.c:676
Code: 00 45 39 4e 10 75 ee 45 3b 6e 14 75 e8 31 c0 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 00 00 00 00 49 8b 7c c6 20 <49> 39 3c c4 75 c5 48 83 c0 01 48 39 c2 75 ec f6 c3 02 74 26 41 8b
RSP: 0018:ffffc90006dc7870 EFLAGS: 00000202
RAX: 0000000000000004 RBX: 0000000000000001 RCX: 000000007b9bc970
RDX: 000000000000000b RSI: 00000000b68975a0 RDI: ffffffff895a9470
RBP: 0000000000000820 R08: 0000000000d001a0 R09: 00000000decd001a
R10: 0000000000000200 R11: 000000000000756b R12: ffffc90006dc78c8
R13: 000000000000000b R14: ffff88802bfe14c0 R15: ffff88816d7001a0
 kasan_save_stack+0x3f/0x50 mm/kasan/common.c:58
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4905
 skb_clone+0x190/0x400 net/core/skbuff.c:2107
 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:386 [inline]
 batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:419 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0x5e5/0x860 net/batman-adv/bat_iv_ogm.c:1700
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5926:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 iowarrior_probe+0x85/0x1220 drivers/usb/misc/iowarrior.c:766
 usb_probe_interface+0x303/0x8f0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:631 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:709
 __driver_probe_device+0x22e/0x480 drivers/base/dd.c:871
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:901
 __device_attach_driver+0x1df/0x340 drivers/base/dd.c:1029
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1101
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1156
 bus_probe_device+0x64/0x160 drivers/base/bus.c:613
 device_add+0x1210/0x1950 drivers/base/core.c:3706
 usb_set_configuration+0xd97/0x1c60 drivers/usb/core/message.c:2268
 usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:631 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:709
 __driver_probe_device+0x22e/0x480 drivers/base/dd.c:871
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:901
 __device_attach_driver+0x1df/0x340 drivers/base/dd.c:1029
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1101
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1156
 bus_probe_device+0x64/0x160 drivers/base/bus.c:613
 device_add+0x1210/0x1950 drivers/base/core.c:3706
 usb_new_device.cold+0x685/0x115c drivers/usb/core/hub.c:2695
 hub_port_connect drivers/usb/core/hub.c:5567 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x314d/0x4af0 drivers/usb/core/hub.c:5953
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 39:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6250 [inline]
 kfree+0x223/0x6c0 mm/slub.c:6565
 iowarrior_delete drivers/usb/misc/iowarrior.c:249 [inline]
 iowarrior_disconnect+0x212/0x270 drivers/usb/misc/iowarrior.c:921
 usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:458
 device_remove drivers/base/dd.c:621 [inline]
 device_remove+0x12a/0x180 drivers/base/dd.c:613
 __device_release_driver drivers/base/dd.c:1352 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1375
 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:657
 device_del+0x376/0x9b0 drivers/base/core.c:3895
 usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
 usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2345
 hub_port_connect drivers/usb/core/hub.c:5407 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x1d0c/0x4af0 drivers/usb/core/hub.c:5953
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888050f49000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 360 bytes inside of
 freed 1024-byte region [ffff888050f49000, ffff888050f49400)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888050f4a800 pfn:0x50f48
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801b842dc0 ffffea00015f2410 ffffea0000d13c10
raw: ffff888050f4a800 000000080010000d 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801b842dc0 ffffea00015f2410 ffffea0000d13c10
head: ffff888050f4a800 000000080010000d 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
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 5753, tgid 5753 (udevd), ts 316157882281, free_ts 314951708929
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x11a6/0x33b0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x27c/0x2bc0 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab mm/slub.c:3467 [inline]
 new_slab+0xa6/0x6c0 mm/slub.c:3525
 refill_objects+0x277/0x420 mm/slub.c:7255
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x375/0x650 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kvmalloc_node_noprof+0x7da/0xa00 mm/slub.c:6832
 bucket_table_alloc.isra.0+0x88/0x460 lib/rhashtable.c:186
 rhashtable_init_noprof+0x43b/0x890 lib/rhashtable.c:1100
 simple_xattrs_init fs/xattr.c:1618 [inline]
 simple_xattrs_alloc+0x5c/0xd0 fs/xattr.c:1641
 class_simple_xattrs_constructor include/linux/xattr.h:165 [inline]
 shmem_initxattrs+0x7d/0x6c0 mm/shmem.c:4237
 security_inode_init_security+0x242/0x370 security/security.c:1370
 shmem_mknod+0x2ce/0x480 mm/shmem.c:3868
 lookup_open.isra.0+0xc47/0x11b0 fs/namei.c:4511
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0x2291/0x31a0 fs/namei.c:4855
 do_file_open+0x20e/0x430 fs/namei.c:4887
page last free pid 8872 tgid 8872 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0x747/0x1040 mm/page_alloc.c:2943
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4905
 locks_alloc_lock fs/locks.c:285 [inline]
 flock_lock_inode+0xcdc/0x11c0 fs/locks.c:1150
 flock_lock_inode_wait fs/locks.c:2163 [inline]
 locks_lock_inode_wait+0x119/0x490 fs/locks.c:2190
 locks_lock_file_wait include/linux/filelock.h:455 [inline]
 __do_sys_flock+0x462/0x4d0 fs/locks.c:2258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888050f49000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888050f49080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888050f49100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff888050f49180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888050f49200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	00 45 39             	add    %al,0x39(%rbp)
   3:	4e 10 75 ee          	rex.WRX adc %r14b,-0x12(%rbp)
   7:	45 3b 6e 14          	cmp    0x14(%r14),%r13d
   b:	75 e8                	jne    0xfffffff5
   d:	31 c0                	xor    %eax,%eax
   f:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  16:	00 00 00 00
  1a:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  21:	00 00 00 00
  25:	49 8b 7c c6 20       	mov    0x20(%r14,%rax,8),%rdi
* 2a:	49 39 3c c4          	cmp    %rdi,(%r12,%rax,8) <-- trapping instruction
  2e:	75 c5                	jne    0xfffffff5
  30:	48 83 c0 01          	add    $0x1,%rax
  34:	48 39 c2             	cmp    %rax,%rdx
  37:	75 ec                	jne    0x25
  39:	f6 c3 02             	test   $0x2,%bl
  3c:	74 26                	je     0x64
  3e:	41                   	rex.B
  3f:	8b                   	.byte 0x8b

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/07 23:50 upstream fcee7d82f27d e358bca5 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Write in iowarrior_write_callback
* Struck through repros no longer work on HEAD.