Avoid slowdowns in xmltok-scan-attributes

* lisp/nxml/xmltok.el (xmltok-scan-attributes): Limit the search
to 10000 characters, to avoid slowdowns due to the quadratic
complexity of the regexp.  Suggested by Stefan Monnier.

1 files changed, 7 insertions, 2 deletions

diff --git a/lisp/nxml/xmltok.el b/lisp/nxml/xmltok.el
index c36d225c7c9..fb852e5ea5e 100644
--- a/lisp/nxml/xmltok.el
+++ b/lisp/nxml/xmltok.el
@@ -734,8 +734,13 @@ and VALUE-END, otherwise a STRING giving the value."
         (atts-needing-normalization nil))
     (while (cond ((or (looking-at (xmltok-attribute regexp))
                       ;; use non-greedy group
-                      (when (looking-at (concat "[^<>\n]+?"
-                                                (xmltok-attribute regexp)))
+                      ;; Limit the search to 10000 characters, to
+                      ;; avoid slowdowns due to the quadratic
+                      ;; complexity of the regexp.  See bug#61514.
+                      (when (with-restriction
+                              (point) (+ (point) 10000)
+                              (looking-at (concat "[^<>\n]+?"
+                                                  (xmltok-attribute regexp))))
                         (unless recovering
                           (xmltok-add-error "Malformed attribute"
                                             (point)