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='2023-07-18 18:16:53 +0200'>2023-07-18</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=22c752fde110ac75d87051d680d6383cd0f95c4e'>gnu: yubico-piv-tool: Use texlive-updmap.cfg in native inputs.</a><span class='msg-avail'>...</span></td><td>Nicolas Goaziou</td></tr>
<tr><td><span title='2023-07-14 12:16:39 -0400'>2023-07-14</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=917a299831361f253ea664f009176b4bbe06900a'>gnu: python-yubikey-manager: Update to 5.1.1.</a><span class='msg-avail'>...</span></td><td>John Kehayias</td></tr>
<tr><td><span title='2023-07-14 12:16:31 -0400'>2023-07-14</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=66f0304e1de40bdc39ba2abc515e2cf8433c8f93'>gnu: python-fido2: Update to 1.1.1.</a><span class='msg-avail'>...</span></td><td>John Kehayias</td></tr>
<tr><td><span title='2023-07-14 12:13:34 -0400'>2023-07-14</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=221806905b68f9b52b90bd5c80722d4a5ab3f353'>gnu: python-pyscard: Update to 2.0.7.</a><span class='msg-avail'>...</span></td><td>John Kehayias</td></tr>
<tr><td><span title='2023-06-02 19:24:21 +0800'>2023-06-02</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=a7d9cd742c3149bb014db95f88d1158d590bc124'>gnu: Add pcsc-cyberjack.</a><span class='msg-avail'>...</span></td><td>Arvid Krein</td></tr>
<tr><td><span title='2023-04-27 20:55:25 +0200'>2023-04-27</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=688d99282b2e4db61de6a58df903378a6b34810f'>gnu: yubico-piv-tool: Update to 2.3.1.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2023-04-24 20:43:01 +0200'>2023-04-24</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=92dd588b81e2b07eff8a083e998224963cfe2959'>Merge remote-tracking branch 'origin/master' into core-updates</a></td><td>Andreas Enge</td></tr>
<tr><td><span title='2023-04-24 12:18:45 +0200'>2023-04-24</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=589aa32fbdb0f4cf7af62e02259db1dd4d332074'>gnu: eid-mw: Update to 5.1.10.</a><span class='msg-avail'>...</span></td><td>Raphaël Mélotte</td></tr>
<tr><td><span title='2023-04-21 00:44:06 -0400'>2023-04-21</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=b42acd88d4575fba85da56306f4084abec28500f'>gnu: libu2f-host: Remove patch-docbook-xml phase.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-04-18 22:06:01 +0200'>2023-04-18</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=7f5e0678938e95987c97852eb640a39cbc9dfe63'>gnu: softhsm: Fix test failure with openssl-3.</a><span class='msg-avail'>...</span></td><td>Timotej Lazar</td></tr>
<tr><td><span title='2023-04-14 17:15:08 -0400'>2023-04-14</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=3bacd3c76a58ebe70f98be654f09cbd4166093ab'>Merge branch 'master' into core-updates.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-03-21 21:45:12 -0400'>2023-03-21</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=f5d502f7f470608012592abbbe1fa3954e496c17'>gnu: Add pcsc-tools.</a><span class='msg-avail'>...</span></td><td>Jake Leporte</td></tr>
<tr><td><span title='2023-03-02 10:55:08 +0000'>2023-03-02</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=7df09ee0ab3e7962ef27859ce87e06a323059284'>Merge remote-tracking branch 'savannah/master' into core-updates</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2023-02-13 18:18:09 +0000'>2023-02-13</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=403066162cefb65b4ad858517722641c6394ffc2'>gnu: libnitrokey: Update to 3.8.</a><span class='msg-avail'>...</span></td><td>Morgan Smith</td></tr>
<tr><td><span title='2023-01-30 12:39:40 +0200'>2023-01-30</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=4cf1acc7f3033b50b0bf19e02c9f522d522d338c'>Merge remote-tracking branch 'origin/master' into core-updates</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2022-12-11 01:00:00 +0100'>2022-12-11</span></td><td><a href='/guix/commit/gnu/packages/security-token.scm?id=a44ca60684b2dd91907a09063ecc72571c3600d3'>gnu: eid-mw: Update to 5.1.8.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>