File CVE-2024-39331.patch of Package emacs.33336
commit c645e1d8205f0f0663ec4a2d27575b238c646c7c
Author: Ihor Radchenko <yantar92@posteo.net>
Date: Fri Jun 21 15:45:25 2024 +0200
org-link-expand-abbrev: Do not evaluate arbitrary unsafe Elisp code
* lisp/org/ol.el (org-link-expand-abbrev): Refuse expanding %(...)
link abbrevs that specify unsafe function. Instead, display a
warning, and do not expand the abbrev. Clear all the text properties
from the returned link, to avoid any potential vulnerabilities caused
by properties that may contain arbitrary Elisp.
---
lisp/org/org.el | 42 ++++++++++++++++++++++++++++++------------
1 file changed, 30 insertions(+), 12 deletions(-)
--- lisp/org/org.el
+++ lisp/org/org.el 2024-07-01 14:02:36.048382417 +0000
@@ -9491,7 +9491,7 @@ property to set."
(defun org-link-expand-abbrev (link)
"Apply replacements as defined in `org-link-abbrev-alist'."
- (if (string-match "^\\([^:]*\\)\\(::?\\(.*\\)\\)?$" link)
+ (if (not (string-match "^\\([^:]*\\)\\(::?\\(.*\\)\\)?$" link)) link
(let* ((key (match-string 1 link))
(as (or (assoc key org-link-abbrev-alist-local)
(assoc key org-link-abbrev-alist)))
@@ -9500,17 +9500,35 @@ property to set."
(if (not as)
link
(setq rpl (cdr as))
- (cond
- ((symbolp rpl) (funcall rpl tag))
- ((string-match "%(\\([^)]+\\))" rpl)
- (replace-match
- (save-match-data
- (funcall (intern-soft (match-string 1 rpl)) tag)) t t rpl))
- ((string-match "%s" rpl) (replace-match (or tag "") t t rpl))
- ((string-match "%h" rpl)
- (replace-match (url-hexify-string (or tag "")) t t rpl))
- (t (concat rpl tag)))))
- link))
+ ;; Drop any potentially dangerous text properties like
+ ;; `modification-hooks' that may be used as an attack vector.
+ (substring-no-properties
+ (cond
+ ((symbolp rpl) (funcall rpl tag))
+ ((string-match "%(\\([^)]+\\))" rpl)
+ (let ((rpl-fun-symbol (intern-soft (match-string 1 rpl))))
+ ;; Using `unsafep-function' is not quite enough because
+ ;; Emacs considers functions like `genenv' safe, while
+ ;; they can potentially be used to expose private system
+ ;; data to attacker if abbreviated link is clicked.
+ (if (or (eq t (get rpl-fun-symbol 'org-link-abbrev-safe))
+ (eq t (get rpl-fun-symbol 'pure)))
+ (replace-match
+ (save-match-data
+ (funcall (intern-soft (match-string 1 rpl)) tag))
+ t t rpl)
+ (org-display-warning
+ (format "Disabling unsafe link abbrev: %s
+You may mark function safe via (put '%s 'org-link-abbrev-safe t)"
+ rpl (match-string 1 rpl)))
+ (setq org-link-abbrev-alist-local (delete as org-link-abbrev-alist-local)
+ org-link-abbrev-alist (delete as org-link-abbrev-alist))
+ link
+ )))
+ ((string-match "%s" rpl) (replace-match (or tag "") t t rpl))
+ ((string-match "%h" rpl)
+ (replace-match (url-hexify-string (or tag "")) t t rpl))
+ (t (concat rpl tag))))))))
;;; Storing and inserting links
