From 42e4450e37905c8765b770c490cd6c64713e5de9 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 8 Apr 2021 15:45:20 +0200 Subject: [PATCH] nl80211: fix beacon head validation commit 9a6847ba1747858ccac53c5aba3e25c54fbdf846 upstream. If the beacon head attribute (NL80211_ATTR_BEACON_HEAD) is too short to even contain the frame control field, we access uninitialized data beyond the buffer. Fix this by checking the minimal required size first. We used to do this until S1G support was added, where the fixed data portion has a different size. Reported-and-tested-by: syzbot+72b99dcf4607e8c770f3@syzkaller.appspotmail.com Suggested-by: Eric Dumazet Fixes: 1d47f1198d58 ("nl80211: correctly validate S1G beacon head") Signed-off-by: Johannes Berg Link: https://lore.kernel.org/r/20210408154518.d9b06d39b4ee.Iff908997b2a4067e8d456b3cb96cab9771d252b8@changeid Signed-off-by: Johannes Berg Signed-off-by: Greg Kroah-Hartman --- net/wireless/nl80211.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 535e34a..0c8b16f 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -209,9 +209,13 @@ static int validate_beacon_head(const struct nlattr *attr, unsigned int len = nla_len(attr); const struct element *elem; const struct ieee80211_mgmt *mgmt = (void *)data; - bool s1g_bcn = ieee80211_is_s1g_beacon(mgmt->frame_control); unsigned int fixedlen, hdrlen; + bool s1g_bcn; + if (len < offsetofend(typeof(*mgmt), frame_control)) + goto err; + + s1g_bcn = ieee80211_is_s1g_beacon(mgmt->frame_control); if (s1g_bcn) { fixedlen = offsetof(struct ieee80211_ext, u.s1g_beacon.variable); -- 2.7.4