From: Markus Theil <markus.theil@tu-ilmenau.de>
Date: Sun, 9 Feb 2020 16:58:56 +0000 (+0100)
Subject: iw: scan: fix buffer over-read in print_ies()
X-Git-Tag: v5.8~41
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=cb13b9dfc0f1625280b5d6ed257b4234d6a6bb6d;p=thirdparty%2Fiw.git

iw: scan: fix buffer over-read in print_ies()

This patch correctly checks, if enough data bytes for parsing IEs are
present (-2 in check for type and length). Furthermore, it adds a
nullptr and length check to ease future fuzzing.

Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
Link: https://lore.kernel.org/r/20200209165902.44110-3-markus.theil@tu-ilmenau.de
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/scan.c b/scan.c
index 94def00..49db7f1 100644
--- a/scan.c
+++ b/scan.c
@@ -2190,7 +2190,10 @@ void print_ies(unsigned char *ie, int ielen, bool unknown,
 		.ie = ie,
 		.ielen = ielen };
 
-	while (ielen >= 2 && ielen >= ie[1]) {
+	if (ie == NULL || ielen < 0)
+		return;
+
+	while (ielen >= 2 && ielen - 2 >= ie[1]) {
 		if (ie[0] < ARRAY_SIZE(ieprinters) &&
 		    ieprinters[ie[0]].name &&
 		    ieprinters[ie[0]].flags & BIT(ptype)) {