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;
 		}
 	    }
ion value='koszko-scripts'>koszko-scripts</option>
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<div class='path'>path: <a href='/guix/log/?id=bbdb686878c8fe0d7983b19e348847acd552ed9e'>root</a>/<a href='/guix/log/build-aux?id=bbdb686878c8fe0d7983b19e348847acd552ed9e'>build-aux</a>/<a href='/guix/log/build-aux/compile-as-derivation.scm?id=bbdb686878c8fe0d7983b19e348847acd552ed9e'>compile-as-derivation.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/build-aux/compile-as-derivation.scm?id=bbdb686878c8fe0d7983b19e348847acd552ed9e&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-09-02 15:43:51 +0200'>2018-09-02</span></td><td><a href='/guix/commit/build-aux/compile-as-derivation.scm?id=20cbd4f5f4d08bc26c22eb40b6c1e55b02e93f23'>compile-as-derivation: Adjust %load-compiled-path.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/compile-as-derivation.scm: Set not only %load-path but also
%load-compiled-path.  This can avoid problems where a stale .go is
loaded.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-09 12:02:27 +0200'>2018-06-09</span></td><td><a href='/guix/commit/build-aux/compile-as-derivation.scm?id=75e24d7b0e19ab2164aecb340e82d07d2b9714e7'>pull: Install the new Guix in a profile.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/pull.scm (%pull-version): New variable.
(build-from-source): Pass #:pull-version to BUILD.
(whole-package-for-legacy, derivation-&gt;manifest-entry): New procedure.
(build-and-install): Rewrite in terms of 'build-and-use-profile'.
* guix/scripts/system.scm (maybe-suggest-running-guix-pull)[latest]:
Switch to "/current".
* scripts/guix.in (augment-load-paths!): Remove use of
~/.config/guix/latest.
* build-aux/compile-as-derivation.scm: Replace "/guix/latest/" with
"/current/share/guile/site/X.Y"
* guix/scripts.scm (warn-about-old-distro)[age]: Check "/current"
instead of "/latest".
* doc/guix.texi (Invoking guix pull): Document it.
* doc/contributing.texi (Running Guix Before It Is Installed): Remove
footnote about abusing ~/.config/guix/latest.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-06-09 12:02:27 +0200'>2018-06-09</span></td><td><a href='/guix/commit/build-aux/compile-as-derivation.scm?id=8a0d9bc8a3f153159d9e239a151c0fa98f1e12d8'>self: Produce a complete package with the 'guix' command.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/self.scm (guix-command): New procedure.
(compiled-guix): Add #:pull-version parameter.
[command, package]: New variables.
Honor PULL-VERSION.
(guix-derivation): Add #:pull-version and pass it to 'compiled-guix'.
* build-aux/build-self.scm (build-program): Add #:pull-version
parameter.  Pass it to 'guix-derivation'.
(build): Add #:pull-version and pass it to 'build-program'.
* build-aux/compile-as-derivation.scm: Pass #:pull-version to BUILD.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-04-08 17:48:25 +0200'>2018-04-08</span></td><td><a href='/guix/commit/build-aux/compile-as-derivation.scm?id=2cfc8d69644af6c53fed9128425e8ff70ad4509f'>build: Add 'as-derivation' target.</a><span class='msg-avail'>...<span class='msg-tooltip'>* build-aux/compile-as-derivation.scm: New file.
* Makefile.am (as-derivation): New target.
(EXTRA_DIST): Add compile-as-derivation.scm.
</span></span></td><td>Ludovic Courtès</td></tr>