From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 11 Jul 2018 14:43:17 +0000 (+0200)
Subject: regexec: Fix off-by-one bug in weight comparison [BZ #23036]
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=68c1bf80978594388157c62fd2edd467d4e8dfb2;p=thirdparty%2Fglibc.git

regexec: Fix off-by-one bug in weight comparison [BZ #23036]

Each weight is prefixed by its length, and the length does not include
itself in the count.  This can be seen clearly from the find_idx
function in string/strxfrm_l.c, for example.  The old code behaved as if
the length itself counted, thus comparing an additional byte after the
weight, leading to spurious comparison failures and incorrect further
partitioning of character equivalence classes.

(cherry picked from commit 7b2f4cedf044ea83f53f6b43a5bf6871eb9ce969)
---

diff --git a/ChangeLog b/ChangeLog
index c862ca21ff4..1c77ca2a6c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2018-07-10  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #23036]
+	* posix/regexec.c (check_node_accept_bytes): When comparing
+	weights, do not compare an extra byte after the end of the
+	weights.
+
 2018-06-29  Sylvain Lesage  <severo@rednegra.net>
 
 	[BZ #22996]
diff --git a/NEWS b/NEWS
index 2e7e7837ac7..c5c78ffd3bf 100644
--- a/NEWS
+++ b/NEWS
@@ -69,6 +69,7 @@ The following bugs are resolved with this release:
   [22947] FAIL: misc/tst-preadvwritev2
   [22963] cs_CZ: Add alternative month names
   [23005] Crash in __res_context_send after memory allocation failure
+  [23036] regexec: Fix off-by-one bug in weight comparison
   [23037] initialize msg_flags to zero for sendmmsg() calls
   [23069] sigaction broken on riscv64-linux-gnu
   [23102] Incorrect parsing of consecutive $ variables in runpath entries
diff --git a/posix/regexec.c b/posix/regexec.c
index 4b1ab4ecffb..21129432d1f 100644
--- a/posix/regexec.c
+++ b/posix/regexec.c
@@ -3848,30 +3848,27 @@ check_node_accept_bytes (const re_dfa_t *dfa, int node_idx,
 	      indirect = (const int32_t *)
 		_NL_CURRENT (LC_COLLATE, _NL_COLLATE_INDIRECTMB);
 	      int32_t idx = findidx (table, indirect, extra, &cp, elem_len);
+	      int32_t rule = idx >> 24;
+	      idx &= 0xffffff;
 	      if (idx > 0)
-		for (i = 0; i < cset->nequiv_classes; ++i)
-		  {
-		    int32_t equiv_class_idx = cset->equiv_classes[i];
-		    size_t weight_len = weights[idx & 0xffffff];
-		    if (weight_len == weights[equiv_class_idx & 0xffffff]
-			&& (idx >> 24) == (equiv_class_idx >> 24))
-		      {
-			int cnt = 0;
-
-			idx &= 0xffffff;
-			equiv_class_idx &= 0xffffff;
-
-			while (cnt <= weight_len
-			       && (weights[equiv_class_idx + 1 + cnt]
-				   == weights[idx + 1 + cnt]))
-			  ++cnt;
-			if (cnt > weight_len)
-			  {
-			    match_len = elem_len;
-			    goto check_node_accept_bytes_match;
-			  }
-		      }
-		  }
+		{
+		  size_t weight_len = weights[idx];
+		  for (i = 0; i < cset->nequiv_classes; ++i)
+		    {
+		      int32_t equiv_class_idx = cset->equiv_classes[i];
+		      int32_t equiv_class_rule = equiv_class_idx >> 24;
+		      equiv_class_idx &= 0xffffff;
+		      if (weights[equiv_class_idx] == weight_len
+			  && equiv_class_rule == rule
+			  && memcmp (weights + idx + 1,
+				     weights + equiv_class_idx + 1,
+				     weight_len) == 0)
+			{
+			  match_len = elem_len;
+			  goto check_node_accept_bytes_match;
+			}
+		    }
+		}
 	    }
 	}
       else