Copied from Debian.

From: Petr Stodulka <pstodulk@redhat.com>
Date: Mon, 14 Sep 2015 18:23:17 +0200
Subject: Upstream fix for heap overflow
Bug-Debian: https://bugs.debian.org/802162
Bug-RedHat: https://bugzilla.redhat.com/show_bug.cgi?id=1260944
Origin: https://bugzilla.redhat.com/attachment.cgi?id=1073002
Forwarded: yes

---
 crypt.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

--- a/crypt.c
+++ b/crypt.c
@@ -465,7 +465,17 @@
     GLOBAL(pInfo->encrypted) = FALSE;
     defer_leftover_input(__G);
     for (n = 0; n < RAND_HEAD_LEN; n++) {
-        b = NEXTBYTE;
+        /* 2012-11-23 SMS.  (OUSPG report.)
+         * Quit early if compressed size < HEAD_LEN.  The resulting
+         * error message ("unable to get password") could be improved,
+         * but it's better than trying to read nonexistent data, and
+         * then continuing with a negative G.csize.  (See
+         * fileio.c:readbyte()).
+         */
+        if ((b = NEXTBYTE) == (ush)EOF)
+        {
+            return PK_ERR;
+        }
         h[n] = (uch)b;
         Trace((stdout, " (%02x)", h[n]));
     }
fs/?id=5b15b42e3f90aea14bbbba38d2bb26574059daa8'>refs</a><a class='active' href='/guix/log/gnu/packages/aux-files/emacs'>log</a><a href='/guix/tree/gnu/packages/aux-files/emacs?id=5b15b42e3f90aea14bbbba38d2bb26574059daa8'>tree</a><a href='/guix/commit/gnu/packages/aux-files/emacs?id=5b15b42e3f90aea14bbbba38d2bb26574059daa8'>commit</a><a href='/guix/diff/gnu/packages/aux-files/emacs?id=5b15b42e3f90aea14bbbba38d2bb26574059daa8'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/aux-files/emacs'>
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<tr><td><span title='2020-03-22 21:17:38 -0400'>2020-03-22</span></td><td><a href='/guix/commit/gnu/packages/aux-files/emacs?id=155f9afde5ce7f1aa72ee0e889d1f9d432896c41'>gnu: emacs: Remove obsolete FIXME comment.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/aux-files/emacs/guix-emacs.el: Remove comment.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-02-27 16:59:07 -0500'>2020-02-27</span></td><td><a href='/guix/commit/gnu/packages/aux-files/emacs?id=9659459f0640ebfd2f662c26e939f38b0a4abf2b'>emacs-build-system: Byte compile the autoload files.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/emacs-build-system.scm (enable-autoloads-compilation)
(validate-compiled-autoloads): Add procedures.
(%standard-phases): Register the new procedures.
* gnu/packages/aux-files/emacs/guix-emacs.el (guix-emacs-find-autoloads):
Remove duplicates in the list of autoload files found.
* guix/build/emacs-utils.scm (expr-&gt;string): Add procedure.
(emacs-batch-eval, emacs-batch-edit-file): Use it.
</span></span></td><td>Maxim Cournoyer</td></tr>