[glibc/ibm/2.28/master] regex: fix read overrun [BZ #24114]

[glibc/ibm/2.28/master] regex: fix read overrun [BZ #24114]

[Tulio Magno Quites Machado Filho]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2aee101ff6075dd97a99982a1ba29e21ec25c52f

commit 2aee101ff6075dd97a99982a1ba29e21ec25c52f
Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Mon Jan 21 11:08:13 2019 -0800

    regex: fix read overrun [BZ #24114]
    
    Problem found by AddressSanitizer, reported by Hongxu Chen in:
    https://debbugs.gnu.org/34140
    * posix/regexec.c (proceed_next_node):
    Do not read past end of input buffer.
    
    (cherry picked from commit 583dd860d5b833037175247230a328f0050dbfe9)

Diff:
---
 ChangeLog       | 8 ++++++++
 posix/regexec.c | 6 ++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index e501112..0ef60fa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-01-31  Paul Eggert  <eggert@cs.ucla.edu>
+
+	regex: fix read overrun [BZ #24114]
+	Problem found by AddressSanitizer, reported by Hongxu Chen in:
+	https://debbugs.gnu.org/34140
+	* posix/regexec.c (proceed_next_node):
+	Do not read past end of input buffer.
+
 2018-11-07  Andreas Schwab  <schwab@suse.de>
 
 	[BZ #23864]
diff --git a/posix/regexec.c b/posix/regexec.c
index 73644c2..06b8487 100644
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -1289,8 +1289,10 @@ 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;
 		}
 	    }