KASAN: use-after-free in nilfs_mdt_destroy

From: butt3rflyh4ck
Date: Mon Mar 22 2021 - 05:06:34 EST

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Hi, guy, I reported a bug found by syzkaller fuzzer with custom
modifications and reproduced in 5.12.0-rc3+ too.

There are use-after-free crashes in nilfs_mdt_destroy in fs/nilfs2/mdt.c.

and there is a latest crash logs as follows:

==================================================================
BUG: KASAN: use-after-free in nilfs_mdt_destroy+0x6f/0x80 fs/nilfs2/mdt.c:485
Read of size 8 at addr ffff8880478f0098 by task syz-executor325/8480

CPU: 1 PID: 8480 Comm: syz-executor325 Not tainted 5.12.0-rc3+ #42
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0xfa/0x151 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x82/0x32c mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
nilfs_mdt_destroy+0x6f/0x80 fs/nilfs2/mdt.c:485
nilfs_free_inode+0x3e/0x60 fs/nilfs2/super.c:167
i_callback+0x3f/0x70 fs/inode.c:223
alloc_inode+0x13e/0x1e0 fs/inode.c:248
iget5_locked fs/inode.c:1148 [inline]
iget5_locked+0x57/0xd0 fs/inode.c:1141
nilfs_iget_locked fs/nilfs2/inode.c:570 [inline]
nilfs_iget+0xb2/0x870 fs/nilfs2/inode.c:579
nilfs_lookup fs/nilfs2/namei.c:63 [inline]
nilfs_lookup+0xfd/0x130 fs/nilfs2/namei.c:54
__lookup_slow+0x255/0x490 fs/namei.c:1626
lookup_slow fs/namei.c:1643 [inline]
walk_component+0x418/0x6a0 fs/namei.c:1939
link_path_walk.part.0+0x6b6/0xc10 fs/namei.c:2266
link_path_walk fs/namei.c:2190 [inline]
path_lookupat.isra.0+0x8d/0x530 fs/namei.c:2419
filename_lookup+0x1a3/0x3e0 fs/namei.c:2453
user_path_at include/linux/namei.h:60 [inline]
vfs_statx+0x13c/0x370 fs/stat.c:195
do_statx+0xd9/0x160 fs/stat.c:590
__do_sys_statx fs/stat.c:613 [inline]
__se_sys_statx fs/stat.c:608 [inline]
__x64_sys_statx+0xba/0x150 fs/stat.c:608
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4505ad
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff7db857c8 EFLAGS: 00000246 ORIG_RAX: 000000000000014c
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004505ad
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000006
RBP: 0000000000000004 R08: 0000000000000000 R09: 00000000004a4099
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff7db857ec
R13: 00007fff7db85810 R14: 00007fff7db857f0 R15: 0000000000000010

Allocated by task 8426:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
____kasan_kmalloc mm/kasan/common.c:506 [inline]
____kasan_kmalloc mm/kasan/common.c:465 [inline]
__kasan_kmalloc+0x99/0xc0 mm/kasan/common.c:515
kasan_kmalloc include/linux/kasan.h:233 [inline]
__kmalloc+0x1c7/0x3d0 mm/slub.c:4055
kmalloc include/linux/slab.h:559 [inline]
kzalloc include/linux/slab.h:684 [inline]
nilfs_mdt_init+0x2c/0x1e0 fs/nilfs2/mdt.c:448
nilfs_dat_read+0x11b/0x2c0 fs/nilfs2/dat.c:489
nilfs_load_super_root fs/nilfs2/the_nilfs.c:120 [inline]
load_nilfs+0x327/0x11c0 fs/nilfs2/the_nilfs.c:269
nilfs_fill_super fs/nilfs2/super.c:1058 [inline]
nilfs_mount+0xab0/0xfe0 fs/nilfs2/super.c:1316
legacy_get_tree+0x105/0x220 fs/fs_context.c:592
vfs_get_tree+0x89/0x2f0 fs/super.c:1497
do_new_mount fs/namespace.c:2903 [inline]
path_mount+0x123b/0x1cc0 fs/namespace.c:3233
do_mount+0xf3/0x110 fs/namespace.c:3246
__do_sys_mount fs/namespace.c:3454 [inline]
__se_sys_mount fs/namespace.c:3431 [inline]
__x64_sys_mount+0x18f/0x230 fs/namespace.c:3431
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x700 kernel/rcu/tree.c:3114
netlink_release+0xd41/0x1c20 net/netlink/af_netlink.c:810
__sock_release+0xcd/0x280 net/socket.c:599
sock_close+0x18/0x20 net/socket.c:1258
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xe0/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x25c/0x270 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
insert_work+0x4a/0x3a0 kernel/workqueue.c:1331
__queue_work+0x4d4/0x1120 kernel/workqueue.c:1497
queue_work_on+0xae/0xc0 kernel/workqueue.c:1524
kref_put include/linux/kref.h:65 [inline]
tty_kref_put drivers/tty/tty_io.c:1589 [inline]
release_tty+0x4e9/0x610 drivers/tty/tty_io.c:1626
tty_release_struct+0x37/0x50 drivers/tty/tty_io.c:1725
tty_release+0xbd2/0x1140 drivers/tty/tty_io.c:1885
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xe0/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x25c/0x270 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff8880478f0000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 152 bytes inside of
2048-byte region [ffff8880478f0000, ffff8880478f0800)
The buggy address belongs to the page:
page:0000000003e87868 refcount:1 mapcount:0 mapping:0000000000000000
index:0xffff8880478f0000 pfn:0x478f0
head:0000000003e87868 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4fff00000010200(slab|head)
raw: 04fff00000010200 ffffea00011e0600 0000000200000002 ffff88800fc42000
raw: ffff8880478f0000 0000000080080007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880478eff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880478f0000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880478f0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880478f0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880478f0180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

the attachment is reproduce.

Regards,
butt3rflyh4ck.

Attachment: repro.cprog
Description: Binary data

Next message: Matthew Wilcox: "Re: [net] 5478fcd0f4: BUG:sleeping_function_called_from_invalid_context_at_include/linux/sched/mm.h"
Previous message: Sergey Senozhatsky: "Re: [PATCH 3/5] cifsd: add file operations"
Next in thread: Ryusuke Konishi: "Re: KASAN: use-after-free in nilfs_mdt_destroy"
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