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]));
     }
7730e388ce420d95c9e045a5dda20d7e7db'>refs</a><a class='active' href='/guix/log/gnu/build/accounts.scm'>log</a><a href='/guix/tree/gnu/build/accounts.scm?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>tree</a><a href='/guix/commit/gnu/build/accounts.scm?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>commit</a><a href='/guix/diff/gnu/build/accounts.scm?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/build/accounts.scm'>
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<div class='path'>path: <a href='/guix/log/?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>root</a>/<a href='/guix/log/gnu?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>gnu</a>/<a href='/guix/log/gnu/build?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>build</a>/<a href='/guix/log/gnu/build/accounts.scm?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db'>accounts.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/build/accounts.scm?id=8b5b87730e388ce420d95c9e045a5dda20d7e7db&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-01-01 15:10:12 +0100'>2022-01-01</span></td><td><a href='/guix/commit/gnu/build/accounts.scm?id=671e6a81804f264ddcdd6fe7579644404da079b8'>system: Allow 'chfn' to change the user's full name.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/52539&gt;.
Reported by Jacob First &lt;jacob.first@member.fsf.org&gt;.

* gnu/build/accounts.scm (allocate-passwd): Add comment as to why
'real-name' is taken from PREVIOUS.  Add (not system?) to the
condition.
* gnu/system.scm (operating-system-etc-service) &lt;login.defs&gt;: Add
"CHFN_RESTRICT".
* gnu/system.scm (%setuid-programs): Add "chfn".
* gnu/system/pam.scm (base-pam-services): Add "chfn".
* doc/guix.texi (User Accounts): Document it.
</span></span></td><td>Ludovic Courtès</td></tr>