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f2fs: fix to avoid NULL pointer dereference f2fs_write_end_io()

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commit d8189834d4348ae608083e1f1f53792cfcc2a9bc upstream.

butt3rflyh4ck reports a bug as below:

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.

general protection fault, probably for non-canonical address
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
RIP: 0010:NODE_MAPPING fs/f2fs/f2fs.h:1972 [inline]
RIP: 0010:f2fs_write_end_io+0x727/0x1050 fs/f2fs/data.c:370
 <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

The root cause is below race case can cause leaving dirty metadata
in f2fs after filesystem is remount as ro:

Thread A				Thread B
- f2fs_ioc_resize_fs
 - f2fs_readonly   --- return false
 - f2fs_resize_fs
					- f2fs_remount
					 - write_checkpoint
					 - set f2fs as ro
  - free_segment_range
   - update meta_inode's data

Then, if f2fs_put_super()  fails to write_checkpoint due to readonly
status, and meta_inode's dirty data will be writebacked after node_inode
is put, finally, f2fs_write_end_io will access NULL pointer on
sbi->node_inode.

Thread A				IRQ context
- f2fs_put_super
 - write_checkpoint fails
 - iput(node_inode)
 - node_inode = NULL
 - iput(meta_inode)
  - write_inode_now
   - f2fs_write_meta_page
					- f2fs_write_end_io
					 - NODE_MAPPING(sbi)
					 : access NULL pointer on node_inode

Fixes: b4b10061ef98 ("f2fs: refactor resize_fs to avoid meta updates in progress")
Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Closes: https://lore.kernel.org/r/1684480657-2375-1-git-send-email-yangtiezhu@loongson.cn
Tested-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chao Yu 2023-05-23 14:17:25 +08:00 committed by Greg Kroah-Hartman
parent 333feb7ba8
commit 982c29e0d2
3 changed files with 20 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/f2fs/f2fs.h
View File

@ -3660,7 +3660,7 @@ block_t f2fs_start_bidx_of_node(unsigned int node_ofs, struct inode *inode);
int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, bool background, bool force,
unsigned int segno);
void f2fs_build_gc_manager(struct f2fs_sb_info *sbi);
int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count);
int f2fs_resize_fs(struct file *filp, __u64 block_count);
int __init f2fs_create_garbage_collection_cache(void);
void f2fs_destroy_garbage_collection_cache(void);

2
fs/f2fs/file.c
View File

@ -3251,7 +3251,7 @@ static int f2fs_ioc_resize_fs(struct file *filp, unsigned long arg)
sizeof(block_count)))
return -EFAULT;
return f2fs_resize_fs(sbi, block_count);
return f2fs_resize_fs(filp, block_count);
}
static int f2fs_ioc_enable_verity(struct file *filp, unsigned long arg)

21
fs/f2fs/gc.c
View File

@ -1992,8 +1992,9 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs)
}
}
int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
int f2fs_resize_fs(struct file *filp, __u64 block_count)
{
struct f2fs_sb_info *sbi = F2FS_I_SB(file_inode(filp));
__u64 old_block_count, shrunk_blocks;
struct cp_control cpc = { CP_RESIZE, 0, 0, 0 };
unsigned int secs;
@ -2031,12 +2032,18 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
return -EINVAL;
}
err = mnt_want_write_file(filp);
if (err)
return err;
shrunk_blocks = old_block_count - block_count;
secs = div_u64(shrunk_blocks, BLKS_PER_SEC(sbi));
/* stop other GC */
if (!down_write_trylock(&sbi->gc_lock))
return -EAGAIN;
if (!down_write_trylock(&sbi->gc_lock)) {
err = -EAGAIN;
goto out_drop_write;
}
/* stop CP to protect MAIN_SEC in free_segment_range */
f2fs_lock_op(sbi);
@ -2056,10 +2063,18 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
out_unlock:
f2fs_unlock_op(sbi);
up_write(&sbi->gc_lock);
out_drop_write:
mnt_drop_write_file(filp);
if (err)
return err;
freeze_super(sbi->sb);
if (f2fs_readonly(sbi->sb)) {
thaw_super(sbi->sb);
return -EROFS;
}
down_write(&sbi->gc_lock);
down_write(&sbi->cp_global_sem);