From: Jouni Malinen <j@w1.fi>
Date: Sat, 23 Feb 2019 14:03:47 +0000 (+0200)
Subject: UBSan: Avoid unsigned integer overflow in utf8_{,un}escape()
X-Git-Tag: hostap_2_8~324
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fed7d8fcba68729fe7de9018422c0006fd00c642;p=thirdparty%2Fhostap.git

UBSan: Avoid unsigned integer overflow in utf8_{,un}escape()

Split the if/while loop condition into two independent steps so that
in_size-- happens only in the case in_size is nonzero. This gets rid of
unnecessary UBSan warnings.

common.c:1087:16: runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type 'size_t' (aka 'unsigned long')
common.c:1076:16: runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type 'size_t' (aka 'unsigned long')
common.c:1119:16: runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type 'size_t' (aka 'unsigned long')

Signed-off-by: Jouni Malinen <j@w1.fi>
---

diff --git a/src/utils/common.c b/src/utils/common.c
index 1eb33705b..f58d2351b 100644
--- a/src/utils/common.c
+++ b/src/utils/common.c
@@ -1,6 +1,6 @@
 /*
  * wpa_supplicant/hostapd / common helper functions, etc.
- * Copyright (c) 2002-2007, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2002-2019, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -1073,7 +1073,8 @@ size_t utf8_unescape(const char *inp, size_t in_size,
 		in_size--;
 	}
 
-	while (in_size--) {
+	while (in_size) {
+		in_size--;
 		if (res_size >= out_size)
 			return 0;
 
@@ -1084,8 +1085,9 @@ size_t utf8_unescape(const char *inp, size_t in_size,
 			return res_size;
 
 		case '\\':
-			if (!in_size--)
+			if (!in_size)
 				return 0;
+			in_size--;
 			inp++;
 			/* fall through */
 
@@ -1116,7 +1118,8 @@ size_t utf8_escape(const char *inp, size_t in_size,
 	if (!in_size)
 		in_size = os_strlen(inp);
 
-	while (in_size--) {
+	while (in_size) {
+		in_size--;
 		if (res_size++ >= out_size)
 			return 0;