| Message ID | 1432282960-4980-1-git-send-email-michal.kazior@tieto.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Johannes Berg |
| Headers | show |
On Fri, 2015-05-22 at 10:22 +0200, Michal Kazior wrote: > There was a possible race between > ieee80211_reconfig() and > ieee80211_delayed_tailroom_dec(). This could > result in inability to transmit data if driver > crashed during roaming or rekeying and subsequent > skbs with insufficient tailroom appeared. > > This race was probably never seen in the wild > because a device driver would have to crash AND > recover within 0.5s which is very unlikely. > > I was able to prove this race exists after > changing the delay to 10s locally and crashing > ath10k via debugfs immediately after GTK > rekeying. In case of ath10k the counter went below > 0. This was harmless but other drivers which > actually require tailroom (e.g. for WEP ICV or > MMIC) could end up with the counter at 0 instead > of >0 and introduce insufficient skb tailroom > failures because mac80211 would not resize skbs > appropriately anymore. > > Fixes: 8d1f7ecd2af5 ("mac80211: defer tailroom counter manipulation when roaming") > Signed-off-by: Michal Kazior <michal.kazior@tieto.com> Applied. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/mac80211/main.c b/net/mac80211/main.c index 99d27babd9f0..674164fe5cdb 100644 --- a/net/mac80211/main.c +++ b/net/mac80211/main.c @@ -246,6 +246,7 @@ static void ieee80211_restart_work(struct work_struct *work) { struct ieee80211_local *local = container_of(work, struct ieee80211_local, restart_work); + struct ieee80211_sub_if_data *sdata; /* wait for scan work complete */ flush_workqueue(local->workqueue); @@ -254,6 +255,8 @@ static void ieee80211_restart_work(struct work_struct *work) "%s called with hardware scan in progress\n", __func__); rtnl_lock(); + list_for_each_entry(sdata, &local->interfaces, list) + flush_delayed_work(&sdata->dec_tailroom_needed_wk); ieee80211_scan_cancel(local); ieee80211_reconfig(local); rtnl_unlock();
There was a possible race between ieee80211_reconfig() and ieee80211_delayed_tailroom_dec(). This could result in inability to transmit data if driver crashed during roaming or rekeying and subsequent skbs with insufficient tailroom appeared. This race was probably never seen in the wild because a device driver would have to crash AND recover within 0.5s which is very unlikely. I was able to prove this race exists after changing the delay to 10s locally and crashing ath10k via debugfs immediately after GTK rekeying. In case of ath10k the counter went below 0. This was harmless but other drivers which actually require tailroom (e.g. for WEP ICV or MMIC) could end up with the counter at 0 instead of >0 and introduce insufficient skb tailroom failures because mac80211 would not resize skbs appropriately anymore. Fixes: 8d1f7ecd2af5 ("mac80211: defer tailroom counter manipulation when roaming") Signed-off-by: Michal Kazior <michal.kazior@tieto.com> --- Notes: v3: * use flush_work() [Johannes] net/mac80211/main.c | 3 +++ 1 file changed, 3 insertions(+)