From: Jouni Malinen <j@w1.fi>
Date: Sun, 18 Oct 2015 16:08:25 +0000 (+0300)
Subject: privsep: Avoid undefined behavior in pointer arithmetic
X-Git-Tag: hostap_2_6~1463
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ceb19ff7a67fc79721c1020a61933de18551891c;p=thirdparty%2Fhostap.git

privsep: Avoid undefined behavior in pointer arithmetic

Reorder terms in a way that no invalid pointers are generated with
pos+len operations. end-pos is always defined (with a valid pos pointer)
while pos+len could end up pointing beyond the end pointer which would
be undefined behavior.

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

diff --git a/src/drivers/driver_privsep.c b/src/drivers/driver_privsep.c
index 1f1676a20..762c12ff4 100644
--- a/src/drivers/driver_privsep.c
+++ b/src/drivers/driver_privsep.c
@@ -161,11 +161,11 @@ wpa_driver_privsep_get_scan_results2(void *priv)
 		return NULL;
 	}
 
-	while (results->num < (size_t) num && pos + sizeof(int) < end) {
+	while (results->num < (size_t) num && end - pos > sizeof(int)) {
 		int len;
 		os_memcpy(&len, pos, sizeof(int));
 		pos += sizeof(int);
-		if (len < 0 || len > 10000 || pos + len > end)
+		if (len < 0 || len > 10000 || len > end - pos)
 			break;
 
 		r = os_malloc(len);