From 7839f70dc125c067ac53e8d89c2028d2b816c9e7 Mon Sep 17 00:00:00 2001
From: Vaibhav Rustagi <vaibhavrustagi@google.com>
Date: Thu, 18 Jun 2020 10:59:32 -0700
Subject: [PATCH] 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.
---
 posix/regexec.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/posix/regexec.c b/posix/regexec.c
index 4b1ab4ecff..1fd10df6c7 100644
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -1272,8 +1272,10 @@ proceed_next_node (const re_match_context_t *mctx, int 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;
 		}
 	    }
-- 
2.27.0.290.gba653c62da-goog