xfs: fix untrusted inode number lookup (4536f2ad) · Commits · 戴 / test

Commit ("xfs: validate untrusted inode numbers during lookup") changes the inode lookup code to do btree lookups for untrusted inode numbers. This change made an invalid assumption about the alignment of inodes and hence incorrectly calculated the first inode in the cluster. As a result, some inode numbers were being incorrectly considered invalid when they were actually valid. The issue was not picked up by the xfstests suite because it always runs fsr and dump (the two utilities that utilise the bulkstat interface) on cache hot inodes and hence the lookup code in the cold cache path was not sufficiently exercised to uncover this intermittent problem. Fix the issue by relaxing the btree lookup criteria and then checking if the record returned contains the inode number we are lookup for. If it we get an incorrect record, then the inode number is invalid. Cc: <stable@kernel.org> Signed-off-by:

Dave Chinner <dchinner@redhat.com> Reviewed-by:

Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_ialloc.c

+10 −6

Original line number	Diff line number	Diff line
		@@ -1213,7 +1213,6 @@ xfs_imap_lookup(
		struct xfs_inobt_rec_incore rec;
		struct xfs_btree_cur *cur;
		struct xfs_buf *agbp;
		xfs_agino_t startino;
		int error;
		int i;

		@@ -1227,13 +1226,13 @@ xfs_imap_lookup(
		}

		/*
		* derive and lookup the exact inode record for the given agino. If the
		* record cannot be found, then it's an invalid inode number and we
		* should abort.
		* Lookup the inode record for the given agino. If the record cannot be
		* found, then it's an invalid inode number and we should abort. Once
		* we have a record, we need to ensure it contains the inode number
		* we are looking up.
		*/
		cur = xfs_inobt_init_cursor(mp, tp, agbp, agno);
		startino = agino & ~(XFS_IALLOC_INODES(mp) - 1);
		error = xfs_inobt_lookup(cur, startino, XFS_LOOKUP_EQ, &i);
		error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i);
		if (!error) {
		if (i)
		error = xfs_inobt_get_rec(cur, &rec, &i);
		@@ -1246,6 +1245,11 @@ xfs_imap_lookup(
		if (error)
		return error;

		/* check that the returned record contains the required inode */
		if (rec.ir_startino > agino \|\|
		rec.ir_startino + XFS_IALLOC_INODES(mp) <= agino)
		return EINVAL;

		/* for untrusted inodes check it is allocated first */
		if ((flags & XFS_IGET_UNTRUSTED) &&
		(rec.ir_free & XFS_INOBT_MASK(agino - rec.ir_startino)))

Admin message