From: Siddh Raman Pant code@siddh.me
commit 15bc8966b6d3a5b9bfe4c9facfa02f2b69b1e5f0 upstream.
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().
Cc: stable@vger.kernel.org Fixes: cd7760e62c2a ("mac80211: add support for CSA in IBSS mode") Link: https://syzkaller.appspot.com/bug?id=05603ef4ae8926761b678d2939a3b2ad28ab9ca... Reported-by: syzbot+b6c9fe29aefe68e4ad34@syzkaller.appspotmail.com Signed-off-by: Siddh Raman Pant code@siddh.me Tested-by: syzbot+b6c9fe29aefe68e4ad34@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20220814151512.9985-1-code@siddh.me Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mac80211/ibss.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/net/mac80211/ibss.c +++ b/net/mac80211/ibss.c @@ -541,6 +541,10 @@ int ieee80211_ibss_finish_csa(struct iee
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,