linux-kernel - [PATCH 3.2 38/74] cfg80211: Validate frequencies nested in NL80211_ATTR_SCAN

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Message-ID: <lsq.1507552234.14568064@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:30:34 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Jouni Malinen" <jouni@....qualcomm.com>,
        "Johannes Berg" <johannes.berg@...el.com>,
        "Srinivas Dasari" <dasaris@....qualcomm.com>
Subject: [PATCH 3.2 38/74] cfg80211: Validate frequencies nested in
 NL80211_ATTR_SCAN_FREQUENCIES

3.2.94-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Srinivas Dasari <dasaris@....qualcomm.com>

commit d7f13f7450369281a5d0ea463cc69890a15923ae upstream.

validate_scan_freqs() retrieves frequencies from attributes
nested in the attribute NL80211_ATTR_SCAN_FREQUENCIES with
nla_get_u32(), which reads 4 bytes from each attribute
without validating the size of data received. Attributes
nested in NL80211_ATTR_SCAN_FREQUENCIES don't have an nla policy.

Validate size of each attribute before parsing to avoid potential buffer
overread.

Fixes: 2a519311926 ("cfg80211/nl80211: scanning (and mac80211 update to use it)")
Signed-off-by: Srinivas Dasari <dasaris@....qualcomm.com>
Signed-off-by: Jouni Malinen <jouni@....qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/wireless/nl80211.c | 4 ++++
 1 file changed, 4 insertions(+)

--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3499,6 +3499,10 @@ static int validate_scan_freqs(struct nl
 	struct nlattr *attr1, *attr2;
 	int n_channels = 0, tmp1, tmp2;
 
+	nla_for_each_nested(attr1, freqs, tmp1)
+		if (nla_len(attr1) != sizeof(u32))
+			return 0;
+
 	nla_for_each_nested(attr1, freqs, tmp1) {
 		n_channels++;
 		/*