md: recovery of RAID array md0
md: md0: recovery done.
==================================================================
BUG: KASAN: use-after-free in r1buf_pool_alloc+0x184/0xbc8 drivers/md/raid1.c:180
Read of size 8 at addr ffff0000ceb25200 by task md0_resync/4508

CPU: 1 PID: 4508 Comm: md0_resync Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
 r1buf_pool_alloc+0x184/0xbc8 drivers/md/raid1.c:180
 mempool_init_node+0x1c4/0x470 mm/mempool.c:221
 mempool_init+0x50/0x68 mm/mempool.c:250
 init_resync drivers/md/raid1.c:2629 [inline]
 raid1_sync_request+0x22c/0x26e4 drivers/md/raid1.c:2679
 md_do_sync+0x2e18/0x36ec drivers/md/md.c:9158
 md_thread+0x1e0/0x3cc drivers/md/md.c:8000
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

Allocated by task 4504:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031
 kmalloc include/linux/slab.h:563 [inline]
 raid1_reshape+0x590/0x102c drivers/md/raid1.c:3289
 chunk_size_store+0x1ec/0x358 drivers/md/md.c:4290
 md_attr_store+0x168/0x234 drivers/md/md.c:5626
 sysfs_kf_write+0x1f8/0x274 fs/sysfs/file.c:140
 kernfs_fop_write_iter+0x390/0x4b4 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3c8/0x7c8 fs/read_write.c:584
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Freed by task 4507:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xbc/0x21c mm/slub.c:3700
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 raid1_reshape+0xc74/0x102c drivers/md/raid1.c:3332
 chunk_size_store+0x1ec/0x358 drivers/md/md.c:4290
 md_attr_store+0x168/0x234 drivers/md/md.c:5626
 sysfs_kf_write+0x1f8/0x274 fs/sysfs/file.c:140
 kernfs_fop_write_iter+0x390/0x4b4 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3c8/0x7c8 fs/read_write.c:584
 ksys_write+0x12c/0x228 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the object at ffff0000ceb25200
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of
 128-byte region [ffff0000ceb25200, ffff0000ceb25280)

The buggy address belongs to the physical page:
page:00000000d7cf963a refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10eb25
flags: 0x5ffc00000000200(slab|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000200 0000000000000000 dead000000000122 ffff0000c0002300
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000ceb25100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000ceb25180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000ceb25200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff0000ceb25280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000ceb25300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Unable to handle kernel paging request at virtual address dfff800000000008
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000008] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4508 Comm: md0_resync Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 02400005 (nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : r1buf_pool_alloc+0x69c/0xbc8 drivers/md/raid1.c:198
lr : r1buf_pool_alloc+0x688/0xbc8 drivers/md/raid1.c:197
sp : ffff800021637450
x29: ffff8000216374a0 x28: 0000000000000087 x27: fffffc000328db74
x26: 0000000000000040 x25: ffff0000d568e440 x24: ffff0000d568e448
x23: 0000000000000cc0 x22: 0000000000000078 x21: dfff800000000000
x20: 0000000000000001 x19: ffff0000d568e448 x18: 1fffe00033e7697e
x17: 0000000000000000 x16: ffff800011b90080 x15: fffffc000330ed00
x14: 0000000000000001 x13: 1fffff8000651b6e x12: 0000000000000000
x11: ff0080000ea37f14 x10: 0000000000000000 x9 : ffff0000d6cf4c00
x8 : 0000000000000008 x7 : fffffc000354a4c0 x6 : fffffc00033349c0
x5 : ffff0000d568e4c8 x4 : ffff0000d568e088 x3 : ffff80000ea37f28
x2 : 0000000000000001 x1 : 0000000000000008 x0 : 0000000000000000
Call trace:
 r1buf_pool_alloc+0x69c/0xbc8 drivers/md/raid1.c:198
 mempool_init_node+0x1c4/0x470 mm/mempool.c:221
 mempool_init+0x50/0x68 mm/mempool.c:250
 init_resync drivers/md/raid1.c:2629 [inline]
 raid1_sync_request+0x22c/0x26e4 drivers/md/raid1.c:2679
 md_do_sync+0x2e18/0x36ec drivers/md/md.c:9158
 md_thread+0x1e0/0x3cc drivers/md/md.c:8000
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
Code: f9400be9 9101011a f9000329 d343ff48 (38756908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	f9400be9 	ldr	x9, [sp, #16]
   4:	9101011a 	add	x26, x8, #0x40
   8:	f9000329 	str	x9, [x25]
   c:	d343ff48 	lsr	x8, x26, #3
* 10:	38756908 	ldrb	w8, [x8, x21] <-- trapping instruction