[btrfs?] KASAN: use-after-free Read in btrfs_search_slot

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1015a148480000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=61a1b0ba1254fab2100e
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16180254480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15306bb4480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98c0bdb4abb3/disk-3f8a27f9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ea228ff02669/vmlinux-3f8a27f9.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e45a876c1c0e/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+61a1b0...@syzkaller.appspotmail.com

BTRFS info (device loop0): has skinny extents
BTRFS info (device loop0): clearing free space tree
BTRFS info (device loop0): clearing 1 ro feature flag
BTRFS info (device loop0): clearing 2 ro feature flag
==================================================================
BUG: KASAN: use-after-free in btrfs_search_slot+0x1cca/0x1ee0 fs/btrfs/ctree.c:2793
Read of size 8 at addr ffff88809b330f70 by task btrfs-ino-cache/30350

CPU: 1 PID: 30350 Comm: btrfs-ino-cache Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
btrfs_search_slot+0x1cca/0x1ee0 fs/btrfs/ctree.c:2793
caching_kthread+0x275/0x970 fs/btrfs/inode-map.c:61
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 30321:
kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
btrfs_alloc_root fs/btrfs/disk-io.c:1220 [inline]
btrfs_read_tree_root+0x94/0x560 fs/btrfs/disk-io.c:1421
btrfs_read_fs_root fs/btrfs/disk-io.c:1467 [inline]
btrfs_get_fs_root+0x239/0x890 fs/btrfs/disk-io.c:1601
btrfs_read_fs_root_no_name fs/btrfs/disk-io.h:80 [inline]
open_ctree+0x469c/0x61e0 fs/btrfs/disk-io.c:3181
btrfs_fill_super fs/btrfs/super.c:1209 [inline]
btrfs_mount_root+0x12e5/0x1830 fs/btrfs/super.c:1613
mount_fs+0xa3/0x310 fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
vfs_kern_mount+0x3c/0x60 fs/namespace.c:951
btrfs_mount+0x23a/0xaa0 fs/btrfs/super.c:1681
mount_fs+0xa3/0x310 fs/super.c:1261
vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
vfs_kern_mount fs/namespace.c:951 [inline]
do_new_mount fs/namespace.c:2492 [inline]
do_mount+0x115c/0x2f50 fs/namespace.c:2822
ksys_mount+0xcf/0x130 fs/namespace.c:3038
__do_sys_mount fs/namespace.c:3052 [inline]
__se_sys_mount fs/namespace.c:3049 [inline]
__x64_sys_mount+0xba/0x150 fs/namespace.c:3049
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8102:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
btrfs_put_fs_root fs/btrfs/disk-io.h:111 [inline]
btrfs_free_fs_root+0x1e6/0x260 fs/btrfs/disk-io.c:3861
btrfs_free_fs_roots+0x2ef/0x4d0 fs/btrfs/disk-io.c:2092
close_ctree+0x306/0x850 fs/btrfs/disk-io.c:4017
generic_shutdown_super+0x144/0x370 fs/super.c:456
kill_anon_super+0x36/0x60 fs/super.c:1032
btrfs_kill_super+0x49/0x550 fs/btrfs/super.c:2221
deactivate_locked_super+0x94/0x160 fs/super.c:329
deactivate_super+0x174/0x1a0 fs/super.c:360
cleanup_mnt+0x1a8/0x290 fs/namespace.c:1098
task_work_run+0x148/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809b330d80
which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 496 bytes inside of
4096-byte region [ffff88809b330d80, ffff88809b331d80)
The buggy address belongs to the page:
page:ffffea00026ccc00 count:1 mapcount:0 mapping:ffff88813bff0dc0 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffffea000289b088 ffffea00023c1008 ffff88813bff0dc0
raw: 0000000000000000 ffff88809b330d80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809b330e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809b330e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809b330f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809b330f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809b331000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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