A null-ptr-deref bug in f2fs_write_end_io

From: butt3rflyh4ck
Date: Fri May 19 2023 - 03:13:43 EST

Hi, there is a null-ptr-deref bug in f2fs_write_end_io in
fs/f2fs/data.c, I reproduce it in the latest kernel too.

#Quick description
When a thread always calls F2FS_IOC_RESIZE_FS to resize fs, if resize
fs is failed, f2fs kernel thread would invoke callback function to
update
f2fs io info, it would call f2fs_write_end_io and may trigger
null-ptr-deref in NODE_MAPPING.
```
static inline struct address_space *NODE_MAPPING(struct f2fs_sb_info *sbi)
{
return sbi->node_inode->i_mapping;
}
```
there is deref in sbi.

#crash log
----------------------------------------
general protection fault, probably for non-canonical address
0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
CPU: 0 PID: 17 Comm: ksoftirqd/0 Not tainted 6.4.0-rc1 #18
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:NODE_MAPPING fs/f2fs/f2fs.h:1972 [inline]
RIP: 0010:f2fs_write_end_io+0x727/0x1050 fs/f2fs/data.c:370
Code: 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 b3 07 00 00 48 8b
44 24 08 4c 8b a8 60 01 00 00 49 8d 7d 30 48 89 f8 48 c1 e8 03 <80> 3c
18 00 0f 85 9c 07 00 00 4d 3b 75 30 0f 84 10 04 00 00 e8 10
RSP: 0018:ffffc9000042fc78 EFLAGS: 00010216
RAX: 0000000000000006 RBX: dffffc0000000000 RCX: 0000000000000100
RDX: ffff888013d18000 RSI: ffffffff83a93a4d RDI: 0000000000000030
RBP: ffffea00009e6900 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00009e6900
R13: 0000000000000000 R14: ffff88802a3cec48 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555faf194000 CR3: 00000000251bd000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
<TASK>
bio_endio+0x5af/0x6c0 block/bio.c:1608
req_bio_endio block/blk-mq.c:761 [inline]
blk_update_request+0x5cc/0x1690 block/blk-mq.c:906
blk_mq_end_request+0x59/0x4c0 block/blk-mq.c:1023
lo_complete_rq+0x1c6/0x280 drivers/block/loop.c:370
blk_complete_reqs+0xad/0xe0 block/blk-mq.c:1101
__do_softirq+0x1d4/0x8ef kernel/softirq.c:571
run_ksoftirqd kernel/softirq.c:939 [inline]
run_ksoftirqd+0x31/0x60 kernel/softirq.c:931
smpboot_thread_fn+0x659/0x9e0 kernel/smpboot.c:164
kthread+0x33e/0x440 kernel/kthread.c:379
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:NODE_MAPPING fs/f2fs/f2fs.h:1972 [inline]
RIP: 0010:f2fs_write_end_io+0x727/0x1050 fs/f2fs/data.c:370
Code: 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 b3 07 00 00 48 8b
44 24 08 4c 8b a8 60 01 00 00 49 8d 7d 30 48 89 f8 48 c1 e8 03 <80> 3c
18 00 0f 85 9c 07 00 00 4d 3b 75 30 0f 84 10 04 00 00 e8 10
RSP: 0018:ffffc9000042fc78 EFLAGS: 00010216
RAX: 0000000000000006 RBX: dffffc0000000000 RCX: 0000000000000100
RDX: ffff888013d18000 RSI: ffffffff83a93a4d RDI: 0000000000000030
RBP: ffffea00009e6900 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00009e6900
R13: 0000000000000000 R14: ffff88802a3cec48 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555faf194000 CR3: 00000000251bd000 CR4: 0000000000750ef0
PKRU: 55555554
-----------------------

# new crash log in latest kernel
---------------------
[ 193.695164][ T8174] loop0: detected capacity change from 0 to 264192
[ 193.696467][ T8174] F2FS-fs (loop0): Magic Mismatch,
valid(0xf2f52010) - read(0x0)
[ 193.696875][ T8174] F2FS-fs (loop0): Can't find valid F2FS
filesystem in 2th superblock
[ 193.698363][ T8174] F2FS-fs (loop0): invalid crc_offset: 0
[ 193.700454][ T8174] F2FS-fs (loop0): Disable nat_bits due to
incorrect cp_ver (4542359912962316977, 0)
[ 193.716594][ T8174] F2FS-fs (loop0): Try to recover 2th superblock, ret: 0
[ 193.717102][ T8174] F2FS-fs (loop0): Mounted with checkpoint
version = 3e17dab1
[ 193.743330][ T8174] F2FS-fs (loop0): For resize: curseg of type 0: 46 ==> 4
[ 193.743904][ T8174] F2FS-fs (loop0): For resize: curseg of type 3: 52 ==> 6
[ 193.745690][ T8174] F2FS-fs (loop0): For resize: curseg of type 4: 50 ==> 8
[ 193.746108][ T8174] F2FS-fs (loop0): For resize: curseg of type 5: 48 ==> 10
[ 193.751857][ T8174] F2FS-fs (loop0): resize_fs failed, should run
fsck to repair!
[ 193.780283][ C0] general protection fault, probably for
non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN
[ 193.781027][ C0] KASAN: null-ptr-deref in range
[0x0000000000000030-0x0000000000000037]
[ 193.781572][ C0] CPU: 0 PID: 17 Comm: ksoftirqd/0 Not tainted
6.4.0-rc2-00163-g2d1bcbc6cd70-dirty #17
[ 193.782201][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX,
1996), BIOS 1.15.0-1 04/01/2014
[ 193.782727][ C0] RIP: 0010:f2fs_write_end_io+0x727/0x1050
[ 193.783083][ C0] Code: 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f
85 b3 07 00 00 48 8b 44 24 08 4c 8b a8 60 01 00 00 49 8d 7d 30 48 89
f8 48 c1 e8 03 <80> 3c 18 00 0f 85 9c 07 00 00 4d 3b 75 30 0f 0
[ 193.784268][ C0] RSP: 0018:ffffc9000042fc78 EFLAGS: 00010216
[ 193.784629][ C0] RAX: 0000000000000006 RBX: dffffc0000000000
RCX: 0000000000000100
[ 193.785109][ C0] RDX: ffff888013d18000 RSI: ffffffff83a9588d
RDI: 0000000000000030
[ 193.785576][ C0] RBP: ffffea000143e740 R08: 0000000000000001
R09: 0000000000000000
[ 193.786051][ C0] R10: 0000000000000000 R11: 0000000000000000
R12: ffffea000143e740
[ 193.786571][ C0] R13: 0000000000000000 R14: ffff888041423738
R15: 0000000000000000
[ 193.787055][ C0] FS: 0000000000000000(0000)
GS:ffff88802ca00000(0000) knlGS:0000000000000000
[ 193.787620][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 193.787997][ C0] CR2: 000056056fd87000 CR3: 000000001b546000
CR4: 00000000000006f0
[ 193.788585][ C0] Call Trace:
[ 193.788863][ C0] <TASK>
[ 193.789115][ C0] ? bio_uninit+0x1b7/0x410
[ 193.789509][ C0] ? f2fs_write_end+0xa80/0xa80
[ 193.790053][ C0] bio_endio+0x5af/0x6c0
[ 193.790522][ C0] blk_update_request+0x5cc/0x1690
[ 193.791171][ C0] blk_mq_end_request+0x59/0x4c0
[ 193.791695][ C0] lo_complete_rq+0x1c6/0x280
[ 193.792247][ C0] blk_complete_reqs+0xad/0xe0
[ 193.792759][ C0] __do_softirq+0x1d4/0x8ef
[ 193.793312][ C0] ? __irq_exit_rcu+0x190/0x190
[ 193.793805][ C0] run_ksoftirqd+0x31/0x60
[ 193.794183][ C0] smpboot_thread_fn+0x659/0x9e0
[ 193.794576][ C0] ? sort_range+0x30/0x30
[ 193.794900][ C0] kthread+0x33e/0x440
[ 193.795263][ C0] ? kthread_complete_and_exit+0x40/0x40
[ 193.795907][ C0] ret_from_fork+0x1f/0x30
[ 193.796324][ C0] </TASK>
[ 193.796689][ C0] Modules linked in:
[ 193.797189][ C0] ---[ end trace 0000000000000000 ]---
[ 193.797635][ C0] RIP: 0010:f2fs_write_end_io+0x727/0x1050
[ 193.798182][ C0] Code: 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f
85 b3 07 00 00 48 8b 44 24 08 4c 8b a8 60 01 00 00 49 8d 7d 30 48 89
f8 48 c1 e8 03 <80> 3c 18 00 0f 85 9c 07 00 00 4d 3b 75 30 0f 0
[ 193.799559][ C0] RSP: 0018:ffffc9000042fc78 EFLAGS: 00010216
[ 193.799945][ C0] RAX: 0000000000000006 RBX: dffffc0000000000
RCX: 0000000000000100
[ 193.800329][ C0] RDX: ffff888013d18000 RSI: ffffffff83a9588d
RDI: 0000000000000030
[ 193.800666][ C0] RBP: ffffea000143e740 R08: 0000000000000001
R09: 0000000000000000
[ 193.801047][ C0] R10: 0000000000000000 R11: 0000000000000000
R12: ffffea000143e740
[ 193.801503][ C0] R13: 0000000000000000 R14: ffff888041423738
R15: 0000000000000000
[ 193.802069][ C0] FS: 0000000000000000(0000)
GS:ffff88802ca00000(0000) knlGS:0000000000000000
[ 193.802804][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 193.803356][ C0] CR2: 000056056fd87000 CR3: 000000001b546000
CR4: 00000000000006f0
[ 193.804046][ C0] Kernel panic - not syncing: Fatal exception in interrupt
[ 193.804748][ C0] Kernel Offset: disabled
[ 193.805086][ C0] Rebooting in 86400 seconds..
----------------------------

If needed, I would provide reproduce.

Regards,
butt3rflyh4ck.



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Active Defense Lab of Venustech