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

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Resolves: RHEL-44691
This commit is contained in:
Jacek Migacz 2024-08-22 14:05:10 +02:00
parent d5803a7a83
commit 361d7975e8
2 changed files with 71 additions and 0 deletions
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68
emacs-org-link-expand-abbrev-unsafe-elisp.patch Normal file
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@ -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

3
emacs.spec
View File

@ -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)