EXT4-fs error (device loop1): ext4_fill_super:4612: comm syz-executor.1: inode #2: comm syz-executor.1: iget: illegal inode #
EXT4-fs (loop1): get root inode failed
EXT4-fs (loop1): mount failed
==================================================================
BUG: KASAN: use-after-free in atomic_fetch_add include/asm-generic/atomic-instrumented.h:111 [inline]
BUG: KASAN: use-after-free in refcount_add include/linux/refcount.h:188 [inline]
BUG: KASAN: use-after-free in refcount_inc include/linux/refcount.h:228 [inline]
BUG: KASAN: use-after-free in get_task_struct include/linux/sched/task.h:112 [inline]
BUG: KASAN: use-after-free in kthread_stop+0x37/0x4a0 kernel/kthread.c:612
Write of size 4 at addr ffff8881e59b3f20 by task syz-executor.1/3615

CPU: 1 PID: 3615 Comm: syz-executor.1 Not tainted 5.4.249-syzkaller-00007-g50533a8b511b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x241 lib/dump_stack.c:118
 print_address_description+0x8c/0x600 mm/kasan/report.c:384
 __kasan_report+0xf3/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 check_memory_region_inline mm/kasan/generic.c:141 [inline]
 check_memory_region+0x272/0x280 mm/kasan/generic.c:191
 atomic_fetch_add include/asm-generic/atomic-instrumented.h:111 [inline]
 refcount_add include/linux/refcount.h:188 [inline]
 refcount_inc include/linux/refcount.h:228 [inline]
 get_task_struct include/linux/sched/task.h:112 [inline]
 kthread_stop+0x37/0x4a0 kernel/kthread.c:612
 ext4_fill_super+0x62bd/0x8d70 fs/ext4/super.c:4811
 mount_bdev+0x267/0x370 fs/super.c:1417
 legacy_get_tree+0xdf/0x170 fs/fs_context.c:647
 vfs_get_tree+0x85/0x260 fs/super.c:1547
 do_new_mount+0x292/0x570 fs/namespace.c:2843
 do_mount+0x688/0xe10 fs/namespace.c:3163
 ksys_mount+0xc2/0xf0 fs/namespace.c:3372
 __do_sys_mount fs/namespace.c:3386 [inline]
 __se_sys_mount fs/namespace.c:3383 [inline]
 __x64_sys_mount+0xb1/0xc0 fs/namespace.c:3383
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Allocated by task 2:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0xd9/0x250 mm/slub.c:2842
 kmem_cache_alloc_node include/linux/slab.h:427 [inline]
 alloc_task_struct_node kernel/fork.c:171 [inline]
 dup_task_struct+0x4f/0x600 kernel/fork.c:874
 copy_process+0x56d/0x3230 kernel/fork.c:1881
 _do_fork+0x197/0x900 kernel/fork.c:2396
 kernel_thread+0x16a/0x1d0 kernel/fork.c:2486
 create_kthread kernel/kthread.c:311 [inline]
 kthreadd+0x3b1/0x4f0 kernel/kthread.c:654
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354

Freed by task 509:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook mm/slub.c:1494 [inline]
 slab_free mm/slub.c:3080 [inline]
 kmem_cache_free+0x10b/0x2c0 mm/slub.c:3096
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch+0x492/0xa00 kernel/rcu/tree.c:2167
 rcu_core+0x4c8/0xcb0 kernel/rcu/tree.c:2387
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292

The buggy address belongs to the object at ffff8881e59b3f00
 which belongs to the cache task_struct of size 3904
The buggy address is located 32 bytes inside of
 3904-byte region [ffff8881e59b3f00, ffff8881e59b4e40)
The buggy address belongs to the page:
page:ffffea0007966c00 refcount:1 mapcount:0 mapping:ffff8881f5cf0a00 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5cf0a00
raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x18f/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4891
 alloc_slab_page+0x39/0x3c0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x440 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x2fe/0x490 mm/slub.c:2667
 __slab_alloc+0x62/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0x109/0x250 mm/slub.c:2842
 kmem_cache_alloc_node include/linux/slab.h:427 [inline]
 alloc_task_struct_node kernel/fork.c:171 [inline]
 dup_task_struct+0x4f/0x600 kernel/fork.c:874
 copy_process+0x56d/0x3230 kernel/fork.c:1881
 _do_fork+0x197/0x900 kernel/fork.c:2396
 __do_sys_clone3 kernel/fork.c:2685 [inline]
 __se_sys_clone3 kernel/fork.c:2672 [inline]
 __x64_sys_clone3+0x2da/0x300 kernel/fork.c:2672
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4953 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4959
 __free_slab+0x221/0x2e0 mm/slub.c:1774
 __slab_free+0x34b/0x360 mm/slub.c:3012
 qlist_free_all+0x43/0xb0 mm/kasan/quarantine.c:167
 quarantine_reduce+0x1d9/0x210 mm/kasan/quarantine.c:260
 __kasan_kmalloc+0x41/0x210 mm/kasan/common.c:507
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc_trace+0xdc/0x260 mm/slub.c:2854
 kmalloc include/linux/slab.h:556 [inline]
 ext4_multi_mount_protect+0x6f6/0xa50 fs/ext4/mmp.c:368
 ext4_fill_super+0x5cc2/0x8d70 fs/ext4/super.c:4434
 mount_bdev+0x267/0x370 fs/super.c:1417
 legacy_get_tree+0xdf/0x170 fs/fs_context.c:647
 vfs_get_tree+0x85/0x260 fs/super.c:1547
 do_new_mount+0x292/0x570 fs/namespace.c:2843
 do_mount+0x688/0xe10 fs/namespace.c:3163
 ksys_mount+0xc2/0xf0 fs/namespace.c:3372

Memory state around the buggy address:
 ffff8881e59b3e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e59b3e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881e59b3f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff8881e59b3f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e59b4000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 3615 at lib/refcount.c:25 refcount_warn_saturate+0x132/0x1a0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 3615 Comm: syz-executor.1 Tainted: G    B             5.4.249-syzkaller-00007-g50533a8b511b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:refcount_warn_saturate+0x132/0x1a0 lib/refcount.c:25
Code: 04 01 48 c7 c7 e0 f0 f9 84 e8 aa 24 0e ff 0f 0b eb a9 e8 c1 69 37 ff c6 05 e3 a9 1c 04 01 48 c7 c7 60 f1 f9 84 e8 8e 24 0e ff <0f> 0b eb 8d e8 a5 69 37 ff c6 05 c8 a9 1c 04 01 48 c7 c7 c0 f1 f9
RSP: 0018:ffff8881e46ff910 EFLAGS: 00010246
RAX: cd2358fd41c2e500 RBX: 0000000000000002 RCX: ffff8881e5f21f80
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000002 R08: ffffffff814d59f2 R09: ffffed103edea9b8
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: ffff8881e59b3f00 R14: 0000000000000000 R15: ffff8881e59b3f20
FS:  00007fad1f4256c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c001463000 CR3: 00000001ecb0f000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 refcount_add include/linux/refcount.h:192 [inline]
 refcount_inc include/linux/refcount.h:228 [inline]
 get_task_struct include/linux/sched/task.h:112 [inline]
 kthread_stop+0x1a5/0x4a0 kernel/kthread.c:612
 ext4_fill_super+0x62bd/0x8d70 fs/ext4/super.c:4811
 mount_bdev+0x267/0x370 fs/super.c:1417
 legacy_get_tree+0xdf/0x170 fs/fs_context.c:647
 vfs_get_tree+0x85/0x260 fs/super.c:1547
 do_new_mount+0x292/0x570 fs/namespace.c:2843
 do_mount+0x688/0xe10 fs/namespace.c:3163
 ksys_mount+0xc2/0xf0 fs/namespace.c:3372
 __do_sys_mount fs/namespace.c:3386 [inline]
 __se_sys_mount fs/namespace.c:3383 [inline]
 __x64_sys_mount+0xb1/0xc0 fs/namespace.c:3383
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
---[ end trace 0fbdaec59927a811 ]---
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 3615 at lib/refcount.c:28 refcount_warn_saturate+0x14e/0x1a0 lib/refcount.c:28
Modules linked in:
CPU: 1 PID: 3615 Comm: syz-executor.1 Tainted: G    B   W         5.4.249-syzkaller-00007-g50533a8b511b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:refcount_warn_saturate+0x14e/0x1a0 lib/refcount.c:28
Code: 04 01 48 c7 c7 60 f1 f9 84 e8 8e 24 0e ff 0f 0b eb 8d e8 a5 69 37 ff c6 05 c8 a9 1c 04 01 48 c7 c7 c0 f1 f9 84 e8 72 24 0e ff <0f> 0b e9 6e ff ff ff e8 86 69 37 ff c6 05 aa a9 1c 04 01 48 c7 c7
RSP: 0018:ffff8881e46ff910 EFLAGS: 00010246
RAX: cd2358fd41c2e500 RBX: 0000000000000003 RCX: ffff8881e5f21f80
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff814d59f2 R09: ffffed103edea9b8
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: ffff8881e59b3f00 R14: 0000000000000000 R15: ffff8881e59b3f20
FS:  00007fad1f4256c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c001463000 CR3: 00000001ecb0f000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 refcount_sub_and_test include/linux/refcount.h:261 [inline]
 refcount_dec_and_test include/linux/refcount.h:281 [inline]
 put_task_struct include/linux/sched/task.h:120 [inline]
 kthread_stop+0x1bc/0x4a0 kernel/kthread.c:619
 ext4_fill_super+0x62bd/0x8d70 fs/ext4/super.c:4811
 mount_bdev+0x267/0x370 fs/super.c:1417
 legacy_get_tree+0xdf/0x170 fs/fs_context.c:647
 vfs_get_tree+0x85/0x260 fs/super.c:1547
 do_new_mount+0x292/0x570 fs/namespace.c:2843
 do_mount+0x688/0xe10 fs/namespace.c:3163
 ksys_mount+0xc2/0xf0 fs/namespace.c:3372
 __do_sys_mount fs/namespace.c:3386 [inline]
 __se_sys_mount fs/namespace.c:3383 [inline]
 __x64_sys_mount+0xb1/0xc0 fs/namespace.c:3383
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
---[ end trace 0fbdaec59927a812 ]---