linux-kernel - [PATCH] cfg80211: further limit wiphy names to 64 bytes

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Date:   Mon, 14 May 2018 20:09:24 -0700
From:   Eric Biggers <ebiggers3@...il.com>
To:     linux-wireless@...r.kernel.org,
        Johannes Berg <johannes@...solutions.net>
Cc:     linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH] cfg80211: further limit wiphy names to 64 bytes

From: Eric Biggers <ebiggers@...gle.com>

wiphy names were recently limited to 128 bytes by commit a7cfebcb7594
("cfg80211: limit wiphy names to 128 bytes").  As it turns out though,
this isn't sufficient because dev_vprintk_emit() needs the syslog header
string "SUBSYSTEM=ieee80211\0DEVICE=+ieee80211:$devname" to fit into 128
bytes.  This triggered the "device/subsystem name too long" WARN when
the device name was >= 90 bytes.  As before, this was reproduced by
syzbot by sending an HWSIM_CMD_NEW_RADIO command to the MAC80211_HWSIM
generic netlink family.

Fix it by further limiting wiphy names to 64 bytes.

Reported-by: syzbot+e64565577af34b3768dc@...kaller.appspotmail.com
Fixes: a7cfebcb7594 ("cfg80211: limit wiphy names to 128 bytes")
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 include/uapi/linux/nl80211.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 9c3630146cec0..271b93783d282 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -2698,7 +2698,7 @@ enum nl80211_attrs {
 #define NL80211_ATTR_KEYS NL80211_ATTR_KEYS
 #define NL80211_ATTR_FEATURE_FLAGS NL80211_ATTR_FEATURE_FLAGS

-#define NL80211_WIPHY_NAME_MAXLEN		128
+#define NL80211_WIPHY_NAME_MAXLEN		64

 #define NL80211_MAX_SUPP_RATES			32
 #define NL80211_MAX_SUPP_HT_RATES		77
-- 
2.17.0