ext4: bubble errors from ext4_find_inline_data_nolock() up to ext4_iget()

If ext4_find_inline_data_nolock() returns an error it needs to get
reflected up to ext4_iget().  In order to fix this,
ext4_iget_extra_inode() needs to return an error (and not return
void).

This is related to "ext4: do not allow external inodes for inline
data" (which fixes CVE-2018-11412) in that in the errors=continue
case, it would be useful to for userspace to receive an error
indicating that file system is corrupted.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Cc: stable@kernel.org

fs/ext4/inode.c

@@ -4701,19 +4701,21 @@ static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
 	}
 }
 
-static inline void ext4_iget_extra_inode(struct inode *inode,
+static inline int ext4_iget_extra_inode(struct inode *inode,
 					 struct ext4_inode *raw_inode,
 					 struct ext4_inode_info *ei)
 {
 	__le32 *magic = (void *)raw_inode +
 			EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
+
 	if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <=
 	    EXT4_INODE_SIZE(inode->i_sb) &&
 	    *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
 		ext4_set_inode_state(inode, EXT4_STATE_XATTR);
-		ext4_find_inline_data_nolock(inode);
+		return ext4_find_inline_data_nolock(inode);
 	} else
 		EXT4_I(inode)->i_inline_off = 0;
+	return 0;
 }
 
 int ext4_get_projid(struct inode *inode, kprojid_t *projid)
@@ -4913,7 +4915,9 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 			ei->i_extra_isize = sizeof(struct ext4_inode) -
 					    EXT4_GOOD_OLD_INODE_SIZE;
 		} else {
-			ext4_iget_extra_inode(inode, raw_inode, ei);
+			ret = ext4_iget_extra_inode(inode, raw_inode, ei);
+			if (ret)
+				goto bad_inode;
 		}
 	}