xfs: don't allow di_size with high bit set

commit ef388e2054feedaeb05399ed654bdb06f385d294 upstream. The on-disk field di_size is used to set i_size, which is a signed integer of loff_t. If the high bit of di_size is set, we'll end up with a negative i_size, which will cause all sorts of problems. Since the VFS won't let us create a file with such length, we should catch them here in the verifier too. Signed-off-by: Darrick J. Wong <[email protected]> Reviewed-by: Dave Chinner <[email protected]> Signed-off-by: Dave Chinner <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
NewEraCracker · Apr 22, 2017 · 0f27d9d · 0f27d9d
1 parent 230a372
commit 0f27d9d
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -304,6 +304,14 @@ xfs_dinode_verify(
 	if (dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))
 		return false;
 
+	/* don't allow invalid i_size */
+	if (be64_to_cpu(dip->di_size) & (1ULL << 63))
+		return false;
+
+	/* No zero-length symlinks. */
+	if (S_ISLNK(be16_to_cpu(dip->di_mode)) && dip->di_size == 0)
+		return false;
+
 	/* only version 3 or greater inodes are extensively verified here */
 	if (dip->di_version < 3)
 		return true;