==================================================================
BUG: KASAN: slab-use-after-free in __bch2_write+0x4868/0x486c fs/bcachefs/io_write.c:1410
Read of size 2 at addr ffff0000dcb3983c by task syz.3.580/9863

CPU: 0 UID: 0 PID: 9863 Comm: syz.3.580 Not tainted 6.12.0-syzkaller-g7b1d1d4cfac0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:484 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x198/0x538 mm/kasan/report.c:488
 kasan_report+0xd8/0x138 mm/kasan/report.c:601
 __asan_report_load2_noabort+0x20/0x2c mm/kasan/report_generic.c:379
 __bch2_write+0x4868/0x486c fs/bcachefs/io_write.c:1410
 bch2_write+0x908/0x15c8 fs/bcachefs/io_write.c:1631
 closure_queue include/linux/closure.h:270 [inline]
 closure_call include/linux/closure.h:432 [inline]
 bch2_writepage_do_io fs/bcachefs/fs-io-buffered.c:449 [inline]
 bch2_writepages+0x224/0x304 fs/bcachefs/fs-io-buffered.c:641
 do_writepages+0x304/0x7cc mm/page-writeback.c:2683
 filemap_fdatawrite_wbc+0x124/0x174 mm/filemap.c:398
 __filemap_fdatawrite_range mm/filemap.c:431 [inline]
 file_write_and_wait_range+0x170/0x254 mm/filemap.c:788
 bch2_fsync+0x14c/0x44c fs/bcachefs/fs-io.c:199
 vfs_fsync_range+0x160/0x19c fs/sync.c:188
 generic_write_sync include/linux/fs.h:2871 [inline]
 bch2_write_iter+0x24fc/0x282c fs/bcachefs/fs-io-buffered.c:1061
 iter_file_splice_write+0x898/0xfdc fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0xec/0x1d8 fs/splice.c:1164
 splice_direct_to_actor+0x438/0xa0c fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0x1e4/0x304 fs/splice.c:1233
 do_sendfile+0x46c/0xbd0 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64 fs/read_write.c:1441 [inline]
 __arm64_sys_sendfile64+0x148/0x3a4 fs/read_write.c:1441
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Allocated by task 9863:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:68
 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:565
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x74/0x8c mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:247 [inline]
 slab_post_alloc_hook mm/slub.c:4085 [inline]
 slab_alloc_node mm/slub.c:4134 [inline]
 kmem_cache_alloc_noprof+0x1c0/0x354 mm/slub.c:4141
 mempool_alloc_slab+0x58/0x74 mm/mempool.c:559
 mempool_alloc_noprof+0x150/0x48c mm/mempool.c:402
 bio_alloc_bioset+0x20c/0x1018 block/bio.c:554
 bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:465 [inline]
 __bch2_writepage+0xcf8/0x1e80 fs/bcachefs/fs-io-buffered.c:599
 write_cache_pages+0xc8/0x20c mm/page-writeback.c:2640
 bch2_writepages+0x13c/0x304 fs/bcachefs/fs-io-buffered.c:639
 do_writepages+0x304/0x7cc mm/page-writeback.c:2683
 filemap_fdatawrite_wbc+0x124/0x174 mm/filemap.c:398
 __filemap_fdatawrite_range mm/filemap.c:431 [inline]
 file_write_and_wait_range+0x170/0x254 mm/filemap.c:788
 bch2_fsync+0x14c/0x44c fs/bcachefs/fs-io.c:199
 vfs_fsync_range+0x160/0x19c fs/sync.c:188
 generic_write_sync include/linux/fs.h:2871 [inline]
 bch2_write_iter+0x24fc/0x282c fs/bcachefs/fs-io-buffered.c:1061
 iter_file_splice_write+0x898/0xfdc fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0xec/0x1d8 fs/splice.c:1164
 splice_direct_to_actor+0x438/0xa0c fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0x1e4/0x304 fs/splice.c:1233
 do_sendfile+0x46c/0xbd0 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64 fs/read_write.c:1441 [inline]
 __arm64_sys_sendfile64+0x148/0x3a4 fs/read_write.c:1441
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Freed by task 6424:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:68
 kasan_save_free_info+0x54/0x6c mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x64/0x8c mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:2342 [inline]
 slab_free_after_rcu_debug+0x120/0x308 mm/slub.c:4629
 rcu_do_batch kernel/rcu/tree.c:2567 [inline]
 rcu_core+0x898/0x1b5c kernel/rcu/tree.c:2823
 rcu_core_si+0x10/0x1c kernel/rcu/tree.c:2840
 handle_softirqs+0x2e0/0xbf8 kernel/softirq.c:554
 __do_softirq+0x14/0x20 kernel/softirq.c:588

Last potentially related work creation:
 kasan_save_stack+0x40/0x6c mm/kasan/common.c:47
 __kasan_record_aux_stack+0xd0/0xec mm/kasan/generic.c:541
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:551
 slab_free_hook mm/slub.c:2303 [inline]
 slab_free mm/slub.c:4579 [inline]
 kmem_cache_free+0x340/0x560 mm/slub.c:4681
 mempool_free_slab+0x28/0x38 mm/mempool.c:566
 mempool_free+0xbc/0x2e8 mm/mempool.c:548
 bio_free+0x200/0x27c block/bio.c:237
 bio_put+0x1b8/0x9dc
 bch2_writepage_io_done+0xeb0/0x1308 fs/bcachefs/fs-io-buffered.c:441
 bch2_write_done+0x2b8/0x8a8 fs/bcachefs/io_write.c:477
 bch2_nocow_write_done+0x74/0xf0 fs/bcachefs/io_write.c:1207
 process_one_work+0x7bc/0x1600 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x97c/0xeec kernel/workqueue.c:3391
 kthread+0x288/0x310 kernel/kthread.c:389
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862

Second to last potentially related work creation:
 kasan_save_stack+0x40/0x6c mm/kasan/common.c:47
 __kasan_record_aux_stack+0xd0/0xec mm/kasan/generic.c:541
 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:551
 insert_work+0x54/0x2d4 kernel/workqueue.c:2183
 __queue_work+0xe20/0x1308 kernel/workqueue.c:2339
 queue_work_on+0xe0/0x1a0 kernel/workqueue.c:2390
 queue_work include/linux/workqueue.h:662 [inline]
 closure_queue include/linux/closure.h:268 [inline]
 closure_put_after_sub+0x1e0/0x304 lib/closure.c:42
 closure_sub+0x4c/0x80 lib/closure.c:61
 bch2_nocow_write+0x31b0/0x353c fs/bcachefs/io_write.c:1367
 __bch2_write+0x469c/0x486c fs/bcachefs/io_write.c:1409
 bch2_write+0x908/0x15c8 fs/bcachefs/io_write.c:1631
 closure_queue include/linux/closure.h:270 [inline]
 closure_call include/linux/closure.h:432 [inline]
 bch2_writepage_do_io fs/bcachefs/fs-io-buffered.c:449 [inline]
 bch2_writepages+0x224/0x304 fs/bcachefs/fs-io-buffered.c:641
 do_writepages+0x304/0x7cc mm/page-writeback.c:2683
 filemap_fdatawrite_wbc+0x124/0x174 mm/filemap.c:398
 __filemap_fdatawrite_range mm/filemap.c:431 [inline]
 file_write_and_wait_range+0x170/0x254 mm/filemap.c:788
 bch2_fsync+0x14c/0x44c fs/bcachefs/fs-io.c:199
 vfs_fsync_range+0x160/0x19c fs/sync.c:188
 generic_write_sync include/linux/fs.h:2871 [inline]
 bch2_write_iter+0x24fc/0x282c fs/bcachefs/fs-io-buffered.c:1061
 iter_file_splice_write+0x898/0xfdc fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0xec/0x1d8 fs/splice.c:1164
 splice_direct_to_actor+0x438/0xa0c fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0x1e4/0x304 fs/splice.c:1233
 do_sendfile+0x46c/0xbd0 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64 fs/read_write.c:1441 [inline]
 __arm64_sys_sendfile64+0x148/0x3a4 fs/read_write.c:1441
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

The buggy address belongs to the object at ffff0000dcb397c0
 which belongs to the cache bio-106 of size 1064
The buggy address is located 124 bytes inside of
 freed 1064-byte region [ffff0000dcb397c0, ffff0000dcb39be8)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11cb38
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x5ffc00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 05ffc00000000040 ffff0000e72e6780 dead000000000122 0000000000000000
raw: 0000000000000000 00000000800d000d 00000001f5000000 0000000000000000
head: 05ffc00000000040 ffff0000e72e6780 dead000000000122 0000000000000000
head: 0000000000000000 00000000800d000d 00000001f5000000 0000000000000000
head: 05ffc00000000002 fffffdffc372ce01 ffffffffffffffff 0000000000000000
head: ffff000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000dcb39700: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff0000dcb39780: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff0000dcb39800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff0000dcb39880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000dcb39900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================