| Message ID | 20220814151512.9985-1-code@siddh.me |
|---|---|
| State | New |
| Headers | show |
| Series | wifi: mac80211: Don't finalize CSA in IBSS mode if state is disconnected | expand |
On Sun, 14 Aug 2022 20:45:12 +0530 Siddh Raman Pant wrote: > When we are not connected to a channel, sending channel "switch" > announcement doesn't make any sense. > > The BSS list is empty in that case. This causes the for loop in > cfg80211_get_bss() to be bypassed, so the function returns NULL > (check line 1424 of net/wireless/scan.c), causing the WARN_ON() > in ieee80211_ibss_csa_beacon() to get triggered (check line 500 > of net/mac80211/ibss.c), which was consequently reported on the > syzkaller dashboard. > > Thus, check if we have an existing connection before generating > the CSA beacon in ieee80211_ibss_finish_csa(). > > Fixes: cd7760e62c2a ("mac80211: add support for CSA in IBSS mode") > Bug report: https://syzkaller.appspot.com/bug?id=05603ef4ae8926761b678d2939a3b2ad28ab9ca6 > Reported-by: syzbot+b6c9fe29aefe68e4ad34@syzkaller.appspotmail.com > Cc: stable@vger.kernel.org Tested-by: syzbot+b6c9fe29aefe68e4ad34@syzkaller.appspotmail.com Syzbot is now booting properly and the test ran successfully. Thanks, Siddh > Signed-off-by: Siddh Raman Pant <code@siddh.me> > --- > The fixes commit is old, and syzkaller shows the problem exists for > 4.19 and 4.14 as well, so CC'd stable list. > > net/mac80211/ibss.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c > index d56890e3fabb..9b283bbc7bb4 100644 > --- a/net/mac80211/ibss.c > +++ b/net/mac80211/ibss.c > @@ -530,6 +530,10 @@ int ieee80211_ibss_finish_csa(struct ieee80211_sub_if_data *sdata) > > sdata_assert_lock(sdata); > > + /* When not connected/joined, sending CSA doesn't make sense. */ > + if (ifibss->state != IEEE80211_IBSS_MLME_JOINED) > + return -ENOLINK; > + > /* update cfg80211 bss information with the new channel */ > if (!is_zero_ether_addr(ifibss->bssid)) { > cbss = cfg80211_get_bss(sdata->local->hw.wiphy, > -- > 2.35.1
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c index d56890e3fabb..9b283bbc7bb4 100644 --- a/net/mac80211/ibss.c +++ b/net/mac80211/ibss.c @@ -530,6 +530,10 @@ int ieee80211_ibss_finish_csa(struct ieee80211_sub_if_data *sdata) sdata_assert_lock(sdata); + /* When not connected/joined, sending CSA doesn't make sense. */ + if (ifibss->state != IEEE80211_IBSS_MLME_JOINED) + return -ENOLINK; + /* update cfg80211 bss information with the new channel */ if (!is_zero_ether_addr(ifibss->bssid)) { cbss = cfg80211_get_bss(sdata->local->hw.wiphy,
When we are not connected to a channel, sending channel "switch" announcement doesn't make any sense. The BSS list is empty in that case. This causes the for loop in cfg80211_get_bss() to be bypassed, so the function returns NULL (check line 1424 of net/wireless/scan.c), causing the WARN_ON() in ieee80211_ibss_csa_beacon() to get triggered (check line 500 of net/mac80211/ibss.c), which was consequently reported on the syzkaller dashboard. Thus, check if we have an existing connection before generating the CSA beacon in ieee80211_ibss_finish_csa(). Fixes: cd7760e62c2a ("mac80211: add support for CSA in IBSS mode") Bug report: https://syzkaller.appspot.com/bug?id=05603ef4ae8926761b678d2939a3b2ad28ab9ca6 Reported-by: syzbot+b6c9fe29aefe68e4ad34@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Siddh Raman Pant <code@siddh.me> --- The fixes commit is old, and syzkaller shows the problem exists for 4.19 and 4.14 as well, so CC'd stable list. net/mac80211/ibss.c | 4 ++++ 1 file changed, 4 insertions(+)