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nilfs2: fix infinite loop in nilfs_mdt_get_block()

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If the disk image that nilfs2 mounts is corrupted and a virtual block
address obtained by block lookup for a metadata file is invalid,
nilfs_bmap_lookup_at_level() may return the same internal return code as
-ENOENT, meaning the block does not exist in the metadata file.

This duplication of return codes confuses nilfs_mdt_get_block(), causing
it to read and create a metadata block indefinitely.

In particular, if this happens to the inode metadata file, ifile,
semaphore i_rwsem can be left held, causing task hangs in lock_mount.

Fix this issue by making nilfs_bmap_lookup_at_level() treat virtual block
address translation failures with -ENOENT as metadata corruption instead
of returning the error code.

Link: https://lkml.kernel.org/r/20230430193046.6769-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+221d75710bde87fa0e97@syzkaller.appspotmail.com
  Link: https://syzkaller.appspot.com/bug?extid=221d75710bde87fa0e97
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ryusuke Konishi 2023-05-01 04:30:46 +09:00 committed by Andrew Morton
parent 29417d292b
commit a6a491c048
1 changed files with 12 additions and 4 deletions
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16
fs/nilfs2/bmap.c
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@ -67,20 +67,28 @@ int nilfs_bmap_lookup_at_level(struct nilfs_bmap *bmap, __u64 key, int level,
down_read(&bmap->b_sem);
ret = bmap->b_ops->bop_lookup(bmap, key, level, ptrp);
if (ret < 0) {
ret = nilfs_bmap_convert_error(bmap, __func__, ret);
if (ret < 0)
goto out;
}
if (NILFS_BMAP_USE_VBN(bmap)) {
ret = nilfs_dat_translate(nilfs_bmap_get_dat(bmap), *ptrp,
&blocknr);
if (!ret)
*ptrp = blocknr;
else if (ret == -ENOENT) {
/*
* If there was no valid entry in DAT for the block
* address obtained by b_ops->bop_lookup, then pass
* internal code -EINVAL to nilfs_bmap_convert_error
* to treat it as metadata corruption.
*/
ret = -EINVAL;
}
}
out:
up_read(&bmap->b_sem);
return ret;
return nilfs_bmap_convert_error(bmap, __func__, ret);
}
int nilfs_bmap_lookup_contig(struct nilfs_bmap *bmap, __u64 key, __u64 *ptrp,