From: Johannes Berg Date: Thu, 8 Apr 2021 13:45:20 +0000 (+0200) Subject: nl80211: fix beacon head validation X-Git-Tag: v5.12-rc7~13^2~8^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9a6847ba1747858ccac53c5aba3e25c54fbdf846;p=thirdparty%2Fkernel%2Flinux.git nl80211: fix beacon head validation 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 --- diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 0d34cca387022..b1df42e4f1eb9 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -229,9 +229,13 @@ 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);