From: Johannes Berg johannes.berg@intel.com
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 eric.dumazet@gmail.com Fixes: 1d47f1198d58 ("nl80211: correctly validate S1G beacon head") Signed-off-by: Johannes Berg johannes.berg@intel.com Link: https://lore.kernel.org/r/20210408154518.d9b06d39b4ee.Iff908997b2a4067e8d456... Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/wireless/nl80211.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -209,9 +209,13 @@ static int validate_beacon_head(const st 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);