syzbot

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BUG: KASAN: slab-use-after-free in __lock_acquire+0xff/0x7c80 kernel/locking/lockdep.c:5005
Read of size 8 at addr ffff88814c260ab8 by task syz.0.656/7748

CPU: 0 PID: 7748 Comm: syz.0.656 Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 __lock_acquire+0xff/0x7c80 kernel/locking/lockdep.c:5005
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
 remove_wait_queue+0x24/0x120 kernel/sched/wait.c:54
 free_poll_entry fs/select.c:132 [inline]
 poll_freewait+0xb1/0x240 fs/select.c:141
 do_sys_poll+0xe5b/0x1150 fs/select.c:1013
 __do_sys_ppoll fs/select.c:1118 [inline]
 __se_sys_ppoll+0x200/0x260 fs/select.c:1098
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc8e2b8ebe9
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:00007fc8e3a09038 EFLAGS: 00000246 ORIG_RAX: 000000000000010f
RAX: ffffffffffffffda RBX: 00007fc8e2db5fa0 RCX: 00007fc8e2b8ebe9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000200000000100
RBP: 00007fc8e2c11e19 R08: 0000000000000008 R09: 0000000000000000
R10: 0000200000000280 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc8e2db6038 R14: 00007fc8e2db5fa0 R15: 00007ffe89026648
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [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+0x269/0x3a0 drivers/comedi/drivers.c:1071
 comedi_test_init+0x8a/0x110 drivers/comedi/drivers/comedi_test.c:834
 do_one_initcall+0x1fd/0x750 init/main.c:1238
 do_initcall_level+0x137/0x1f0 init/main.c:1300
 do_initcalls+0x69/0xd0 init/main.c:1316
 kernel_init_freeable+0x3d2/0x570 init/main.c:1553
 kernel_init+0x1d/0x1c0 init/main.c:1443
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Freed by task 7751:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1806 [inline]
 slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1832
 slab_free mm/slub.c:3816 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3829
 comedi_device_detach_cleanup drivers/comedi/drivers.c:171 [inline]
 comedi_device_detach+0x363/0x6f0 drivers/comedi/drivers.c:207
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:833 [inline]
 comedi_unlocked_ioctl+0xbd0/0xf90 drivers/comedi/comedi_fops.c:2156
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88814c260a00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 184 bytes inside of
 freed 256-byte region [ffff88814c260a00, ffff88814c260b00)

The buggy address belongs to the physical page:
page:ffffea0005309800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14c260
head:ffffea0005309800 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
ksm flags: 0x57ff00000000840(slab|head|node=1|zone=2|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 057ff00000000840 ffff888017841b40 ffffea0005309600 dead000000000003
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 14293216575, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2120
 alloc_slab_page+0x5d/0x170 mm/slub.c:1876
 allocate_slab mm/slub.c:2023 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2076
 ___slab_alloc+0xc6d/0x12f0 mm/slub.c:3230
 __slab_alloc mm/slub.c:3329 [inline]
 __slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc_node mm/slub.c:3475 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3524
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 bus_add_driver+0x162/0x640 drivers/base/bus.c:659
 driver_register+0x23a/0x310 drivers/base/driver.c:246
 do_one_initcall+0x1fd/0x750 init/main.c:1238
 do_initcall_level+0x137/0x1f0 init/main.c:1300
 do_initcalls+0x69/0xd0 init/main.c:1316
 kernel_init_freeable+0x3d2/0x570 init/main.c:1553
 kernel_init+0x1d/0x1c0 init/main.c:1443
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88814c260980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88814c260a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88814c260a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff88814c260b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88814c260b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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