[syzbot] [block?] KASAN: slab-use-after-free Read in update_io_ticks (5)

[syzbot <syzbot+8be85719817f5c3d8a9d@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    0e35b9b6ec0f Merge tag 'mm-hotfixes-stable-2026-07-06-17-4..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ba0f39580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=20c9876b0f77b546
dashboard link: https://syzkaller.appspot.com/bug?extid=8be85719817f5c3d8a9d
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-0e35b9b6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2a17ca6db8f5/vmlinux-0e35b9b6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c885024dccba/bzImage-0e35b9b6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8be85719817f5c3d8a9d@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in update_io_ticks+0xa9/0x280 block/blk-core.c:1064
Read of size 8 at addr ffff88803236b9a8 by task kworker/u4:6/176

CPU: 0 UID: 0 PID: 176 Comm: kworker/u4:6 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: loop0 loop_rootcg_workfn
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 update_io_ticks+0xa9/0x280 block/blk-core.c:1064
 blk_account_io_done+0x188/0x870 block/blk-mq.c:1082
 __blk_mq_end_request_acct block/blk-mq.c:1125 [inline]
 __blk_mq_end_request+0x2cf/0x6c0 block/blk-mq.c:1131
 lo_rw_aio_complete drivers/block/loop.c:337 [inline]
 lo_rw_aio+0xcd4/0xf20 drivers/block/loop.c:405
 do_req_filebacked drivers/block/loop.c:431 [inline]
 loop_handle_cmd drivers/block/loop.c:1921 [inline]
 loop_process_work+0x95e/0x11c0 drivers/block/loop.c:1956
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5324:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4612 [inline]
 slab_alloc_node mm/slub.c:4945 [inline]
 kmem_cache_alloc_lru_noprof+0x2aa/0x5f0 mm/slub.c:4978
 bdev_alloc_inode+0x29/0x90 block/bdev.c:380
 alloc_inode+0x6a/0x1b0 fs/inode.c:338
 new_inode+0x1f/0x170 fs/inode.c:1174
 bdev_alloc+0x24/0x370 block/bdev.c:464
 add_partition+0x1c3/0x8e0 block/partitions/core.c:328
 blk_add_partition block/partitions/core.c:566 [inline]
 blk_add_partitions block/partitions/core.c:635 [inline]
 bdev_disk_changed+0xc3e/0x17a0 block/partitions/core.c:695
 loop_reread_partitions drivers/block/loop.c:443 [inline]
 loop_set_status+0x9f7/0xd50 drivers/block/loop.c:1272
 loop_set_status64 drivers/block/loop.c:1368 [inline]
 lo_ioctl+0xc14/0x1fc0 drivers/block/loop.c:1554
 blkdev_ioctl+0x5e3/0x740 block/ioctl.c:797
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5287:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2705 [inline]
 slab_free mm/slub.c:6405 [inline]
 kmem_cache_free+0x182/0x650 mm/slub.c:6532
 rcu_do_batch kernel/rcu/tree.c:2645 [inline]
 rcu_core+0x78b/0x10a0 kernel/rcu/tree.c:2897
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3159 [inline]
 call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3279
 destroy_inode fs/inode.c:392 [inline]
 evict+0x987/0xb50 fs/inode.c:849
 device_release+0xc4/0x1f0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x222/0x550 lib/kobject.c:737
 blkdev_release+0x15/0x20 block/fops.c:680
 __fput+0x418/0xa50 fs/file_table.c:512
 fput_close_sync+0x11f/0x240 fs/file_table.c:617
 __do_sys_close fs/open.c:1511 [inline]
 __se_sys_close fs/open.c:1496 [inline]
 __x64_sys_close+0x7e/0x110 fs/open.c:1496
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88803236b980
 which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
 freed 2792-byte region [ffff88803236b980, ffff88803236c468)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32368
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888040428e81
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801ca81140 dead000000000122 0000000000000000
raw: 0000000000000000 00000008000b000b 00000000f5000000 ffff888040428e81
head: 04fff00000000040 ffff88801ca81140 dead000000000122 0000000000000000
head: 0000000000000000 00000008000b000b 00000000f5000000 ffff888040428e81
head: 04fff00000000003 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 Reclaimable, gfp_mask 0xd20d0(__GFP_RECLAIMABLE|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 19037798701, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3294 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3408
 new_slab mm/slub.c:3454 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7338
 refill_sheaf mm/slub.c:2832 [inline]
 __pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4703
 alloc_from_pcs mm/slub.c:4801 [inline]
 slab_alloc_node mm/slub.c:4933 [inline]
 kmem_cache_alloc_lru_noprof+0x389/0x5f0 mm/slub.c:4978
 bdev_alloc_inode+0x29/0x90 block/bdev.c:380
 alloc_inode+0x6a/0x1b0 fs/inode.c:338
 new_inode+0x1f/0x170 fs/inode.c:1174
 bdev_alloc+0x24/0x370 block/bdev.c:464
 __alloc_disk_node+0x11f/0x600 block/genhd.c:1465
 __blk_alloc_disk+0x105/0x1d0 block/genhd.c:1523
 pmem_attach_disk+0x4d9/0xe10 drivers/nvdimm/pmem.c:509
 nvdimm_bus_probe+0x332/0x6c0 drivers/nvdimm/bus.c:91
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:706
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88803236b880: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
 ffff88803236b900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803236b980: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88803236ba00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88803236ba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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