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BUG: KASAN: use-after-free in btrfs_printk+0x421/0x46b fs/btrfs/super.c:245
Read of size 8 at addr ffff88802c13c6a0 by task syz-executor.2/28646

CPU: 1 PID: 28646 Comm: syz-executor.2 Not tainted 5.10.0-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+0x137/0x1be lib/dump_stack.c:118
 print_address_description+0x6c/0x660 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report+0x136/0x1e0 mm/kasan/report.c:562
 btrfs_printk+0x421/0x46b fs/btrfs/super.c:245
 device_list_add+0x1a94/0x1d60 fs/btrfs/volumes.c:943
 btrfs_scan_one_device+0x2e1/0x460 fs/btrfs/volumes.c:1354
 btrfs_mount_root+0x46e/0xb60 fs/btrfs/super.c:1634
 legacy_get_tree+0xea/0x180 fs/fs_context.c:592
 vfs_get_tree+0x88/0x270 fs/super.c:1549
 fc_mount fs/namespace.c:978 [inline]
 vfs_kern_mount+0xc9/0x160 fs/namespace.c:1008
 btrfs_mount+0x345/0xa80 fs/btrfs/super.c:1732
 legacy_get_tree+0xea/0x180 fs/fs_context.c:592
 vfs_get_tree+0x88/0x270 fs/super.c:1549
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x17b4/0x2a20 fs/namespace.c:3205
 do_mount fs/namespace.c:3218 [inline]
 __do_sys_mount fs/namespace.c:3426 [inline]
 __se_sys_mount+0x28c/0x320 fs/namespace.c:3403
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x46090a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 8a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f0550ed7a88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f0550ed7b20 RCX: 000000000046090a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f0550ed7ae0
RBP: 00007f0550ed7ae0 R08: 00007f0550ed7b20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020016b00

The buggy address belongs to the page:
page:00000000de540802 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x2c13c
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea00008dc908 ffff88813fffb910 0000000000000000
raw: 0000000000000000 0000000000000002 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88802c13c580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802c13c600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88802c13c680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff88802c13c700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802c13c780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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