(image-jpeg-p): Don't search beyond length of data.

diff --git a/lisp/image.el b/lisp/image.el
index 25d05c9902fcaf95ecff282db0730cf6a92e15b5..5f603ccdd12802d8ba12eb9bc136f0bd5acea6fb 100644 (file)
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -67,7 +67,8 @@ We accept the tag Exif because that is the same format."
            (when (and (>= code #xe0) (<= code #xef))
              ;; APP0 LEN1 LEN2 "JFIF\0"
              (throw 'jfif
-                    (string-match "JFIF\\|Exif" (substring data i (+ i nbytes)))))
+                    (string-match "JFIF\\|Exif"
+                                  (substring data i (min (+ i nbytes) len)))))
            (setq i (+ i 1 nbytes))))))))