md: recovery of RAID array md0
md: md0: recovery done.
==================================================================
BUG: KASAN: use-after-free in r1buf_pool_free+0x105/0x110 drivers/md/raid1.c:225
Read of size 4 at addr ffff88802353ed88 by task md0_resync/16317

CPU: 1 PID: 16317 Comm: md0_resync Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 r1buf_pool_free+0x105/0x110 drivers/md/raid1.c:225
 mempool_exit+0x1c7/0x2b0 mm/mempool.c:155
 close_sync drivers/md/raid1.c:1699 [inline]
 raid1_sync_request+0x3b5/0x2fb0 drivers/md/raid1.c:2688
 md_do_sync+0x3701/0x40f0 drivers/md/md.c:9110
 md_thread+0x27a/0x4e0 drivers/md/md.c:7981
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 8432:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xaf/0xe0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:607 [inline]
 raid1_reshape+0x785/0x15f0 drivers/md/raid1.c:3296
 update_raid_disks+0x4e4/0x670 drivers/md/md.c:7358
 raid_disks_store+0x10b/0x4f0 drivers/md/md.c:4262
 md_attr_store+0xdd/0x130 drivers/md/md.c:5643
 kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 16315:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 raid1_reshape+0x1142/0x15f0 drivers/md/raid1.c:3339
 chunk_size_store+0x2a1/0x430 drivers/md/md.c:4328
 md_attr_store+0xdd/0x130 drivers/md/md.c:5643
 kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88802353ed80
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 8 bytes inside of
 16-byte region [ffff88802353ed80, ffff88802353ed90)
The buggy address belongs to the page:
page:ffffea00008d4f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802353ed00 pfn:0x2353e
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0001844300 0000000400000004 ffff888016c413c0
raw: ffff88802353ed00 000000008080006d 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4194, ts 184215176533, free_ts 184206399427
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 __alloc_pages_node include/linux/gfp.h:570 [inline]
 alloc_slab_page mm/slub.c:1782 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xb6/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 __kmalloc_node+0x142/0x3a0 mm/slub.c:4456
 kmalloc_node include/linux/slab.h:630 [inline]
 kvmalloc_node+0x84/0x130 mm/util.c:619
 xt_jumpstack_alloc net/netfilter/x_tables.c:1377 [inline]
 xt_replace_table+0x160/0x750 net/netfilter/x_tables.c:1416
 __do_replace+0x16f/0x9f0 net/ipv4/netfilter/ip_tables.c:1063
 do_replace net/ipv4/netfilter/ip_tables.c:1140 [inline]
 do_ipt_set_ctl+0xa9b/0xd70 net/ipv4/netfilter/ip_tables.c:1633
 nf_setsockopt+0x25f/0x280 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0x29c3/0x31e0 net/ipv4/ip_sockglue.c:1442
 tcp_setsockopt+0x229/0x1e60 net/ipv4/tcp.c:3722
 __sys_setsockopt+0x2bf/0x3d0 net/socket.c:2213
 __do_sys_setsockopt net/socket.c:2224 [inline]
 __se_sys_setsockopt net/socket.c:2221 [inline]
 __x64_sys_setsockopt+0xb1/0xc0 net/socket.c:2221
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 tlb_batch_list_free mm/mmu_gather.c:62 [inline]
 tlb_finish_mmu+0x28b/0x370 mm/mmu_gather.c:374
 exit_mmap+0x3d0/0x640 mm/mmap.c:3218
 __mmput+0x115/0x390 kernel/fork.c:1133
 exit_mm+0x632/0x7b0 kernel/exit.c:557
 do_exit+0x5b8/0x2110 kernel/exit.c:877
 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004
 get_signal+0x7eb/0x12e0 kernel/signal.c:2913
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:157 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88802353ec80: fa fb fc fc fa fb fc fc 00 00 fc fc 00 03 fc fc
 ffff88802353ed00: fb fb fc fc 00 01 fc fc fa fb fc fc 00 00 fc fc
>ffff88802353ed80: fa fb fc fc 00 01 fc fc fa fb fc fc 00 00 fc fc
                      ^
 ffff88802353ee00: fa fb fc fc fa fb fc fc fa fb fc fc 00 00 fc fc
 ffff88802353ee80: 00 00 fc fc fa fb fc fc fa fb fc fc fa fb fc fc
==================================================================