mac80211: free sta in sta_info_insert_finish() on errors

commit 7bc40aedf24d31d8bea80e1161e996ef4299fb10 upstream.

If sta_info_insert_finish() fails, we currently keep the station
around and free it only in the caller, but there's only one such
caller and it always frees it immediately.

As syzbot found, another consequence of this split is that we can
put things that sleep only into __cleanup_single_sta() and not in
sta_info_free(), but this is the only place that requires such of
sta_info_free() now.

Change this to free the station in sta_info_insert_finish(), in
which case we can still sleep. This will also let us unify the
cleanup code later.

Cc: stable@vger.kernel.org
Fixes: dcd479e10a05 ("mac80211: always wind down STA state")
Reported-by: syzbot+32c6c38c4812d22f2f0b@syzkaller.appspotmail.com
Reported-by: syzbot+4c81fe92e372d26c4246@syzkaller.appspotmail.com
Reported-by: syzbot+6a7fe9faf0d1d61bc24a@syzkaller.appspotmail.com
Reported-by: syzbot+abed06851c5ffe010921@syzkaller.appspotmail.com
Reported-by: syzbot+b7aeb9318541a1c709f1@syzkaller.appspotmail.com
Reported-by: syzbot+d5a9416c6cafe53b5dd0@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20201112112201.ee6b397b9453.I9c31d667a0ea2151441cc64ed6613d36c18a48e0@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 8a9bbcfefbca6c7bf0deeb91f43af0bf5fa1b4cf..bdcc6cb60b1c86b7c63e1fca8d146efcb8b4d74d 100644 (file)
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -601,7 +601,7 @@ static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU)
  out_drop_sta:
        local->num_sta--;
        synchronize_net();
-       __cleanup_single_sta(sta);
+       cleanup_single_sta(sta);
  out_err:
        mutex_unlock(&local->sta_mtx);
        kfree(sinfo);
@@ -620,19 +620,13 @@ int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU)
 
        err = sta_info_insert_check(sta);
        if (err) {
+               sta_info_free(local, sta);
                mutex_unlock(&local->sta_mtx);
                rcu_read_lock();
-               goto out_free;
+               return err;
        }
 
-       err = sta_info_insert_finish(sta);
-       if (err)
-               goto out_free;
-
-       return 0;
- out_free:
-       sta_info_free(local, sta);
-       return err;
+       return sta_info_insert_finish(sta);
 }
 
 int sta_info_insert(struct sta_info *sta)