From c1df932c0574c13ab3ce72e969c9647ff3aaad68 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 27 Nov 2015 21:59:41 +0100 Subject: [PATCH] mac80211: fix off-channel mgmt-tx uninitialized variable usage In the last change here, I neglected to update the cookie in one code path: when a mgmt-tx has no real cookie sent to userspace as it doesn't wait for a response, but is off-channel. The original code used the SKB pointer as the cookie and always assigned the cookie to the TX SKB in ieee80211_start_roc_work(), but my change turned this around and made the code rely on a valid cookie being passed in. Unfortunately, the off-channel no-wait TX path wasn't assigning one at all, resulting in an uninitialized stack value being used. This wasn't handed back to userspace as a cookie (since in the no-wait case there isn't a cookie), but it was tested for non-zero to distinguish between mgmt-tx and off-channel. Fix this by assigning a dummy non-zero cookie unconditionally, and get rid of a misleading comment and some dead code while at it. I'll clean up the ACK SKB handling separately later. Fixes: 3b79af973cf4 ("mac80211: stop using pointers as userspace cookies") Signed-off-by: Johannes Berg --- net/mac80211/cfg.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c index c2bd1b6a6922..da471eef07bb 100644 --- a/net/mac80211/cfg.c +++ b/net/mac80211/cfg.c @@ -3454,8 +3454,12 @@ static int ieee80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev, goto out_unlock; } } else { - /* for cookie below */ - ack_skb = skb; + /* Assign a dummy non-zero cookie, it's not sent to + * userspace in this case but we rely on its value + * internally in the need_offchan case to distinguish + * mgmt-tx from remain-on-channel. + */ + *cookie = 0xffffffff; } if (!need_offchan) { -- 2.20.1