Process accounting resumed
==================================================================
BUG: KASAN: use-after-free in add_chain fs/minix/itree_common.c:14 [inline]
BUG: KASAN: use-after-free in get_branch fs/minix/itree_common.c:52 [inline]
BUG: KASAN: use-after-free in get_block+0x69a/0x1600 fs/minix/itree_common.c:160
Read of size 2 at addr ffff8880669aa18a by task syz-executor.0/22157

CPU: 0 PID: 22157 Comm: syz-executor.0 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1f0/0x31e lib/dump_stack.c:118
 print_address_description+0x66/0x5a0 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report+0x132/0x1d0 mm/kasan/report.c:530
 add_chain fs/minix/itree_common.c:14 [inline]
 get_branch fs/minix/itree_common.c:52 [inline]
 get_block+0x69a/0x1600 fs/minix/itree_common.c:160
 __block_write_begin_int+0x708/0x1a00 fs/buffer.c:2012
 __block_write_begin fs/buffer.c:2062 [inline]
 block_write_begin+0x59/0x280 fs/buffer.c:2121
 minix_write_begin+0x38/0x1f0 fs/minix/inode.c:412
 generic_perform_write+0x23b/0x4e0 mm/filemap.c:3299
 __generic_file_write_iter+0x22b/0x4e0 mm/filemap.c:3428
 generic_file_write_iter+0x4a6/0x650 mm/filemap.c:3460
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write fs/read_write.c:484 [inline]
 __vfs_write+0x52f/0x6e0 fs/read_write.c:497
 __kernel_write+0x120/0x350 fs/read_write.c:516
 do_acct_process+0xec6/0x12b0 kernel/acct.c:522
 acct_pin_kill+0x27/0x130 kernel/acct.c:174
 pin_kill+0x218/0x6a0 fs/fs_pin.c:44
 mnt_pin_kill+0x9d/0x160 fs/fs_pin.c:81
 cleanup_mnt+0x48c/0x4e0 fs/namespace.c:1111
 task_work_run+0x137/0x1c0 kernel/task_work.c:135
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:216 [inline]
 __prepare_exit_to_usermode+0x14c/0x1e0 arch/x86/entry/common.c:246
 do_syscall_64+0x7f/0xe0 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb29
Code: Bad RIP value.
RSP: 002b:00007f1525560c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 000000000050b9e0 RCX: 000000000045cb29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000500
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000c8d R14: 00000000004ceea7 R15: 00007f15255616d4

The buggy address belongs to the page:
page:ffffea00019a6a80 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x1
flags: 0xfffe0000000000()
raw: 00fffe0000000000 ffffea0000979708 ffffea00019ad188 0000000000000000
raw: 0000000000000001 0000000000000001 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880669aa080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880669aa100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880669aa180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff8880669aa200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880669aa280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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