KASAN: use-after-free Read in remove_wait_queue

Status: upstream: reported C repro on 2025/08/03 01:02
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+800e15dbad458bb691ea@syzkaller.appspotmail.com
First crash: 368d, last: 346d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/08/24 linux-6.1.y (ToT) 0bc96de781b4 C [report] KASAN: use-after-free Read in remove_wait_queue
2025/08/24 upstream (ToT) 8d245acc1e88 C Didn't crash
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in remove_wait_queue (3) kernfs 19 syz, C inconclusive 123 1298d 1724d 22/29 fixed on 2023/02/24 13:50
linux-4.14 KASAN: use-after-free Read in remove_wait_queue (2) 19 syz, C error 7 1616d 2312d 0/1 upstream: reported C repro on 2020/04/07 06:03
linux-5.15 KASAN: use-after-free Read in remove_wait_queue 19 syz, C done 25 347d 368d 2/3 upstream: reported C repro on 2025/08/03 00:30
upstream KASAN: use-after-free Read in remove_wait_queue (2) fs 19 syz, C 4 3070d 3080d 5/29 fixed on 2018/06/07 13:52
android-49 KASAN: use-after-free Read in remove_wait_queue 19 syz, C 6 3087d 3097d 2/3 fixed on 2018/03/05 12:02
linux-4.14 KASAN: use-after-free Read in remove_wait_queue 19 1 2536d 2536d 0/1 auto-closed as invalid on 2019/12/24 15:10
upstream KASAN: use-after-free Read in remove_wait_queue fs 19 syz, C 7 3087d 3096d 4/29 fixed on 2018/02/26 20:04
linux-4.19 BUG: corrupted list in remove_wait_queue 8 syz, C 31139 1248d 2674d 0/1 upstream: reported C repro on 2019/04/10 16:06
upstream KASAN: slab-use-after-free Read in remove_wait_queue input usb 19 3 1139d 1141d 0/29 auto-obsoleted due to no activity on 2023/10/01 17:55
linux-6.6 KASAN: slab-use-after-free Read in remove_wait_queue 19 syz 13 342d 367d 0/2 auto-obsoleted due to no activity on 2025/11/06 12:40
upstream BUG: corrupted list in remove_wait_queue (2) fs 19 syz, C done done 61 168d 560d 0/29 auto-obsoleted due to no activity on 2026/05/21 04:08
▶ ▼ Fix bisection attempts (5)
Created Duration User Patch Repo Result
2026/05/23 11:25 15m fix candidate upstream error job log
2026/03/25 12:55 1m fix candidate upstream error job log
2026/02/22 17:34 1m fix candidate upstream error job log
2026/01/23 12:26 1m fix candidate upstream error job log
2025/08/08 19:33 2h12m fix candidate upstream OK (0) job log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0xf7/0x7c50 kernel/locking/lockdep.c:4919
Read of size 8 at addr ffff88814a9956b8 by task syz.0.17/4424

CPU: 0 PID: 4424 Comm: syz.0.17 Not tainted 6.1.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 __lock_acquire+0xf7/0x7c50 kernel/locking/lockdep.c:4919
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 remove_wait_queue+0x20/0x120 kernel/sched/wait.c:54
 free_poll_entry fs/select.c:132 [inline]
 poll_freewait+0x99/0x210 fs/select.c:141
 do_sys_poll+0xe8a/0x11f0 fs/select.c:1013
 __do_sys_ppoll fs/select.c:1118 [inline]
 __se_sys_ppoll+0x1fc/0x260 fs/select.c:1098
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fefffd8ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff000bd5038 EFLAGS: 00000246 ORIG_RAX: 000000000000010f
RAX: ffffffffffffffda RBX: 00007feffffb5fa0 RCX: 00007fefffd8ebe9
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000200000000100
RBP: 00007fefffe11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feffffb6038 R14: 00007feffffb5fa0 R15: 00007ffd2a8a16c8
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 __comedi_device_postconfig_async drivers/comedi/drivers.c:666 [inline]
 __comedi_device_postconfig drivers/comedi/drivers.c:723 [inline]
 comedi_device_postconfig+0x496/0xc50 drivers/comedi/drivers.c:758
 comedi_auto_config+0x265/0x3a0 drivers/comedi/drivers.c:1071
 comedi_test_init+0x8f/0x127 drivers/comedi/drivers/comedi_test.c:832
 do_one_initcall+0x214/0x7a0 init/main.c:1298
 do_initcall_level+0x137/0x1e4 init/main.c:1371
 do_initcalls+0x4b/0x8a init/main.c:1387
 kernel_init_freeable+0x3fa/0x5ac init/main.c:1626
 kernel_init+0x19/0x1b0 init/main.c:1514
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 4425:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3674
 comedi_device_detach_cleanup drivers/comedi/drivers.c:171 [inline]
 comedi_device_detach+0x35f/0x6e0 drivers/comedi/drivers.c:207
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:829 [inline]
 comedi_unlocked_ioctl+0xb6b/0xf20 drivers/comedi/comedi_fops.c:2151
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88814a995600
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 184 bytes inside of
 256-byte region [ffff88814a995600, ffff88814a995700)

The buggy address belongs to the physical page:
page:ffffea00052a6500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14a994
head:ffffea00052a6500 order:1 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000010200 0000000000000000 dead000000000122 ffff888017441b40
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 11625821495, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115
 alloc_slab_page+0x5d/0x160 mm/slub.c:1794
 allocate_slab mm/slub.c:1939 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1992
 ___slab_alloc+0xbc6/0x1220 mm/slub.c:3180
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3437
 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 bus_add_driver+0xda/0x5a0 drivers/base/bus.c:604
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 __hid_register_driver+0x126/0x170 drivers/hid/hid-core.c:2910
 do_one_initcall+0x214/0x7a0 init/main.c:1298
 do_initcall_level+0x137/0x1e4 init/main.c:1371
 do_initcalls+0x4b/0x8a init/main.c:1387
 kernel_init_freeable+0x3fa/0x5ac init/main.c:1626
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88814a995580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88814a995600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88814a995680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff88814a995700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88814a995780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (24):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/24 09:10 linux-6.1.y 0bc96de781b4 bf27483f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 21:12 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 17:18 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 15:23 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 12:35 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 09:44 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 06:51 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 05:20 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 03:51 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 02:16 linux-6.1.y 3594f306da12 7368264b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/24 08:43 linux-6.1.y 0bc96de781b4 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/24 08:43 linux-6.1.y 0bc96de781b4 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/20 13:09 linux-6.1.y 0bc96de781b4 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/20 13:09 linux-6.1.y 0bc96de781b4 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/19 21:56 linux-6.1.y 0bc96de781b4 254a27c1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/19 21:54 linux-6.1.y 0bc96de781b4 254a27c1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/19 21:07 linux-6.1.y 0bc96de781b4 254a27c1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/19 12:59 linux-6.1.y 0bc96de781b4 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/19 12:59 linux-6.1.y 0bc96de781b4 523f460e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 19:44 linux-6.1.y 3594f306da12 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 01:25 linux-6.1.y 3594f306da12 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 01:05 linux-6.1.y 3594f306da12 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 01:05 linux-6.1.y 3594f306da12 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
2025/08/03 01:02 linux-6.1.y 3594f306da12 7368264b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in remove_wait_queue
* Struck through repros no longer work on HEAD.