Fix <https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9169>.

Taken from this upstream commit, sans ChangeLog updates:
https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=583dd860d5b833037175247230a328f0050dbfe9

diff --git a/posix/regexec.c b/posix/regexec.c
index 91d5a797b8..084b1222d9 100644
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -1293,8 +1293,10 @@ proceed_next_node (const re_match_context_t *mctx, Idx nregs, regmatch_t *regs,
 	      else if (naccepted)
 		{
 		  char *buf = (char *) re_string_get_buffer (&mctx->input);
-		  if (memcmp (buf + regs[subexp_idx].rm_so, buf + *pidx,
-			      naccepted) != 0)
+		  if (mctx->input.valid_len - *pidx < naccepted
+		      || (memcmp (buf + regs[subexp_idx].rm_so, buf + *pidx,
+				  naccepted)
+			  != 0))
 		    return -1;
 		}
 	    }
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<tr><td><span title='2023-08-16 11:24:10 -0400'>2023-08-16</span></td><td><a href='/guix/commit/gnu/tests/desktop.scm?id=132ddca5a4fb6d789f98866b5bf85be95306c969'>gnu: elogind: Update to 252.9.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/freedesktop.scm (elogind): Update to 252.9.
[source]: Replace elogind-revert-polkit-detection.patch with
elogind-fix-rpath.patch in patches.
[configure-flags]: Add the dbussystemservicedir, dbussessionservicedir,
dbussystemservicedir and dbus-interfaces-dir flags.
[phases] &lt;use-global-hook-directory&gt; Update list of patched files.
&lt;adjust-tests&gt; Update substitutions, and skip the copy_holes test.
[native-inputs]: Add python-jinja2.
[inputs]: Add util-linux:lib.
* gnu/services/desktop.scm (elogind-dbus-service)
&lt;elogind-dbus-service-wrapper&gt;: Add a symlink to elogind's
share/dbus-1/system.d to expose D-Bus policy configurations.
* gnu/tests/desktop.scm (run-elogind-test): Adjust expected result for the new
"linger" value.
* gnu/packages/patches/elogind-revert-polkit-detection.patch: Delete file.
* gnu/packages/patches/elogind-fix-rpath.patch: New file.
* gnu/local.mk (dist_patch_DATA): Update.

Series-to: 64938@debbugs.gnu.org
Series-prefix: elogind-updates
Series-version: 2
Series-changes: 2
- Fix elogind system test
- Install D-Bus policy files in elogind-dbus-service-wrapper
- Remove duplicate 'dbussystemservicedir' configure flag
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-05-14 23:14:25 +0200'>2023-05-14</span></td><td><a href='/guix/commit/gnu/tests/desktop.scm?id=150367c84da8766dc0358ff4878b9e17dbea6a40'>tests: elogind: Wait until 'elogind' is up.</a><span class='msg-avail'>...<span class='msg-tooltip'>Previously we could find ourselves typing in too early.

* gnu/tests/desktop.scm (run-elogind-test)["login on tty1"]: Wait for
'elogind in to 'term-tty1.
["screendump"]: New test.
</span></span></td><td>Ludovic Courtès</td></tr>