jfs: Regular file corruption check

The reproducer builds a corrupted file on disk with a negative i_size value.
Add a check when opening this file to avoid subsequent operation failures.

Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=630f6d40b3ccabc8e96e
Tested-by: [email protected]
Signed-off-by: Edward Adam Davis <[email protected]>
Signed-off-by: Dave Kleikamp <[email protected]>

Author: ea1davis

fs/jfs/file.c

@@ -44,6 +44,9 @@ static int jfs_open(struct inode *inode, struct file *file)
 {
 	int rc;
 
+	if (S_ISREG(inode->i_mode) && inode->i_size < 0)
+		return -EIO;
+
 	if ((rc = dquot_file_open(inode, file)))
 		return rc;