org-link-expand-abbrev: Do not evaluate arbitrary unsafe Elisp code

Resolves: RHEL-44691

emacs-org-link-expand-abbrev-unsafe-elisp.patch

@@ -0,0 +1,68 @@
+From f4cc61636947b5c2f0afc67174dd369fe3277aa8 Mon Sep 17 00:00:00 2001
+From: Ihor Radchenko <yantar92@posteo.net>
+Date: Tue, 18 Jun 2024 13:06:44 +0200
+Subject: 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/ol.el | 40 +++++++++++++++++++++++++++++-----------
+ 1 file changed, 29 insertions(+), 11 deletions(-)
+
+diff --git a/lisp/org/ol.el b/lisp/org/ol.el
+index 7a7f4f5..8a556c7 100644
+--- a/lisp/org/ol.el
++++ b/lisp/org/ol.el
+@@ -1152,17 +1152,35 @@ Abbreviations are defined in `org-link-abbrev-alist'."
+       (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)))))))
++        ;; 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))))))))
+ 
+ (defun org-link-open (link &optional arg)
+   "Open a link object LINK.
+-- 
+cgit v1.1
+

emacs.spec

@@ -36,6 +36,7 @@ Patch9:        emacs-ob-latex-command-injection-vulnerability.patch
 Patch10:       emacs-consider-org-file-contents-unsafe.patch
 Patch11:       emacs-mark-contents-untrusted.patch
 Patch12:       emacs-latex-preview.patch
+Patch13:       emacs-org-link-expand-abbrev-unsafe-elisp.patch
 BuildRequires: gcc
 BuildRequires: atk-devel
 BuildRequires: cairo-devel
@@ -206,6 +207,7 @@ Development header files for Emacs.
 %patch10 -p1 -b .consider-org-file-contents-unsafe
 %patch11 -p1 -b .mark-contents-untrusted
 %patch12 -p1 -b .latex-preview
+%patch13 -p1 -b .org-link-expand-abbrev-unsafe-elisp
 autoconf
 
 # We prefer our emacs.desktop file
@@ -501,6 +503,7 @@ rm %{buildroot}%{_datadir}/icons/hicolor/scalable/mimetypes/emacs-document23.svg
 - org-file-contents: Consider all remote files unsafe (CVE-2024-30205)
 - Make Gnus treats inline MIME contents as untrusted (CVE-2024-30203)
 - Add protection for LaTeX preview (CVE-2024-30204)
+- org-link-expand-abbrev: Do not evaluate arbitrary unsafe Elisp code (CVE-2024-39331)
 
 * Sun Apr 2 2023 Jacek Migacz <jmigacz@redhat.com> - 1:27.2-9
 - Fix etags local command injection vulnerability (#2175190)