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BUG: KASAN: use-after-free in btrfs_printk+0x38b/0x40c fs/btrfs/super.c:245
Read of size 8 at addr ffff88806ff106a0 by task systemd-udevd/17502

CPU: 1 PID: 17502 Comm: systemd-udevd 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+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 btrfs_printk+0x38b/0x40c fs/btrfs/super.c:245
 device_list_add.cold+0x99/0x31e fs/btrfs/volumes.c:943
 btrfs_scan_one_device+0x339/0x4a0 fs/btrfs/volumes.c:1354
 btrfs_control_ioctl+0x12a/0x2d0 fs/btrfs/super.c:2327
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fa7dbdba017
Code: 00 00 00 48 8b 05 81 7e 2b 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 51 7e 2b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe0c7e5dd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa7dbdba017
RDX: 00007ffe0c7e5df0 RSI: 0000000090009427 RDI: 000000000000000f
RBP: 00007ffe0c7e5df0 R08: 0000000000000000 R09: 000000000000000d
R10: fffffffffffffead R11: 0000000000000246 R12: 000000000000000f
R13: 0000000000000000 R14: 0000557b1fe23170 R15: 0000557b1fe13d70

Allocated by task 26531:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 kmalloc_node include/linux/slab.h:575 [inline]
 kvmalloc_node+0xb4/0xf0 mm/util.c:575
 kvmalloc include/linux/mm.h:765 [inline]
 kvzalloc include/linux/mm.h:773 [inline]
 btrfs_mount_root+0x117/0xbb0 fs/btrfs/super.c:1613
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 fc_mount fs/namespace.c:978 [inline]
 vfs_kern_mount.part.0+0xd3/0x170 fs/namespace.c:1008
 vfs_kern_mount+0x3c/0x60 fs/namespace.c:995
 btrfs_mount+0x234/0xa60 fs/btrfs/super.c:1732
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x13ad/0x20c0 fs/namespace.c:3205
 do_mount fs/namespace.c:3218 [inline]
 __do_sys_mount fs/namespace.c:3426 [inline]
 __se_sys_mount fs/namespace.c:3403 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3403
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 26531:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3420 [inline]
 kfree+0xe8/0x240 mm/slab.c:3758
 kvfree+0x42/0x50 mm/util.c:604
 deactivate_locked_super+0x94/0x160 fs/super.c:335
 btrfs_mount_root+0x772/0xbb0 fs/btrfs/super.c:1678
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 fc_mount fs/namespace.c:978 [inline]
 vfs_kern_mount.part.0+0xd3/0x170 fs/namespace.c:1008
 vfs_kern_mount+0x3c/0x60 fs/namespace.c:995
 btrfs_mount+0x234/0xa60 fs/btrfs/super.c:1732
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x13ad/0x20c0 fs/namespace.c:3205
 do_mount fs/namespace.c:3218 [inline]
 __do_sys_mount fs/namespace.c:3426 [inline]
 __se_sys_mount fs/namespace.c:3403 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3403
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88806ff10000
 which belongs to the cache kmalloc-16k of size 16384
The buggy address is located 1696 bytes inside of
 16384-byte region [ffff88806ff10000, ffff88806ff14000)
The buggy address belongs to the page:
page:0000000039644dc3 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6ff10
head:0000000039644dc3 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 ffffea0001eba408 ffffea0001a6f008 ffff888010040b00
raw: 0000000000000000 ffff88806ff10000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88806ff10580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806ff10600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88806ff10680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88806ff10700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806ff10780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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