Merge tag 'xfs-4.17-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs fixes from Darrick Wong:
 "Here are a few more bug fixes for xfs for 4.17-rc4. Most of them are
  fixes for bad behavior.

  This series has been run through a full xfstests run during LSF and
  through a quick xfstests run against this morning's master, with no
  major failures reported.

  Summary:

   - Enhance inode fork verifiers to prevent loading of corrupted
     metadata.

   - Fix a crash when we try to convert extents format inodes to btree
     format, we run out of space, but forget to revert the in-core state
     changes.

   - Fix file size checks when doing INSERT_RANGE that could cause files
     to end up negative size if there previously was an extent mapped at
     s_maxbytes.

   - Fix a bug when doing a remove-then-add ATTR_REPLACE xattr update
     where we forget to clear ATTR_REPLACE after the remove, which
     causes the attr to be lost and the fs to shut down due to (what it
     thinks is) inconsistent in-core state"

* tag 'xfs-4.17-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: don't fail when converting shortform attr to long form during ATTR_REPLACE
  xfs: prevent creating negative-sized file via INSERT_RANGE
  xfs: set format back to extents if xfs_bmap_extents_to_btree
  xfs: enhance dinode verifier

1 files changed, 9 insertions, 5 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 299aee4b7b0b..eed073cc4778 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -778,22 +778,26 @@ xfs_file_fallocate(
 		if (error)
 			goto out_unlock;
 	} else if (mode & FALLOC_FL_INSERT_RANGE) {
-		unsigned int blksize_mask = i_blocksize(inode) - 1;
+		unsigned int	blksize_mask = i_blocksize(inode) - 1;
+		loff_t		isize = i_size_read(inode);
 
-		new_size = i_size_read(inode) + len;
 		if (offset & blksize_mask || len & blksize_mask) {
 			error = -EINVAL;
 			goto out_unlock;
 		}
 
-		/* check the new inode size does not wrap through zero */
-		if (new_size > inode->i_sb->s_maxbytes) {
+		/*
+		 * New inode size must not exceed ->s_maxbytes, accounting for
+		 * possible signed overflow.
+		 */
+		if (inode->i_sb->s_maxbytes - isize < len) {
 			error = -EFBIG;
 			goto out_unlock;
 		}
+		new_size = isize + len;
 
 		/* Offset should be less than i_size */
-		if (offset >= i_size_read(inode)) {
+		if (offset >= isize) {
 			error = -EINVAL;
 			goto out_unlock;
 		}