bug#29868: [PATCH 0/1] regex stack overflow in gdb-jsonify-buffer

bug#29868: [PATCH 0/1] regex stack overflow in gdb-jsonify-buffer

[David McFarland]

https://stackoverflow.com/questions/2882488/debugging-in-emacs-with-gud-often-results-in-stack-overflow-error

In some of my C++ projects, gdb will happily print 60+k characters for the value
of a local, which causes a stack overflow in the regex used by
gdb-jsonify-buffer. This patch instead looks for the start of a string literal
and uses (forward-sexp) to skip it, which was proposed in the answer to the
stackoverflow question above. This results in the same output in the tests that
I've done, but I wouldn't say it's been extensively tested.

David McFarland (1):
  Fix regex stack overflow when parsing complex gdb locals

 lisp/progmodes/gdb-mi.el | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

-- 
2.15.1

bug#29868: [PATCH 1/1] Fix regex stack overflow when parsing complex gdb locals

[David McFarland]

* lisp/progmodes/gdb-mi.el (gdb-jsonify-buffer): Skip string literals
with (forward-sexp) instead of matching with regex.

Copyright-paperwork-exempt: yes
---
 lisp/progmodes/gdb-mi.el | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lisp/progmodes/gdb-mi.el b/lisp/progmodes/gdb-mi.el
index 58552759b9..84b8c6b44b 100644
--- a/lisp/progmodes/gdb-mi.el
+++ b/lisp/progmodes/gdb-mi.el
@@ -2717,10 +2717,10 @@ If `default-directory' is remote, full file names are adapted accordingly."
               (insert "]"))))))
     (goto-char (point-min))
     (insert "{")
-    (let ((re (concat "\\([[:alnum:]-_]+\\)=\\({\\|\\[\\|\"\"\\|"
-                      gdb--string-regexp "\\)")))
+    (let ((re (concat "\\([[:alnum:]-_]+\\)=")))
       (while (re-search-forward re nil t)
-        (replace-match "\"\\1\":\\2" nil nil)))
+        (replace-match "\"\\1\":" nil nil)
+        (if (eq (char-after) ?\") (forward-sexp) (forward-char))))
     (goto-char (point-max))
     (insert "}")))
 
-- 
2.15.1

bug#29868: [PATCH 1/1] Fix regex stack overflow when parsing complex gdb locals

[Eli Zaretskii]

> From: David McFarland <corngood@gmail.com>
> Date: Wed, 27 Dec 2017 11:32:11 -0400
> Cc: David McFarland <corngood@gmail.com>
> 
> * lisp/progmodes/gdb-mi.el (gdb-jsonify-buffer): Skip string literals
> with (forward-sexp) instead of matching with regex.
> 
> Copyright-paperwork-exempt: yes

Thanks, pushed to the master branch.