Commit d536f997 authored May 01, 2023 by Ryusuke Konishi Committed by Greg Kroah-Hartman May 17, 2023

nilfs2: fix infinite loop in nilfs_mdt_get_block()

commit a6a491c048882e7e424d407d32cba0b52d9ef2bf upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e9c5412c

fs/nilfs2/bmap.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -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,