cfg80211: always check for scan end on P2P device
If a P2P device wdev is removed while it has a scan, then the
scan completion might crash later as it is already freed by
that time. To avoid the crash always check the scan completion
when the P2P device is being removed for some reason. If the
driver already canceled it, don't want and free it, otherwise
warn and leak it to avoid later crashes.
In order to do this, locking needs to be changed away from the
rdev mutex (which can't always be guaranteed). For now, use
the sched_scan_mtx instead, I'll rename it to just scan_mtx in
a later patch.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d44ab21..58e13a8 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -4702,14 +4702,19 @@
if (!rdev->ops->scan)
return -EOPNOTSUPP;
- if (rdev->scan_req)
- return -EBUSY;
+ mutex_lock(&rdev->sched_scan_mtx);
+ if (rdev->scan_req) {
+ err = -EBUSY;
+ goto unlock;
+ }
if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
n_channels = validate_scan_freqs(
info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]);
- if (!n_channels)
- return -EINVAL;
+ if (!n_channels) {
+ err = -EINVAL;
+ goto unlock;
+ }
} else {
enum ieee80211_band band;
n_channels = 0;
@@ -4723,23 +4728,29 @@
nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp)
n_ssids++;
- if (n_ssids > wiphy->max_scan_ssids)
- return -EINVAL;
+ if (n_ssids > wiphy->max_scan_ssids) {
+ err = -EINVAL;
+ goto unlock;
+ }
if (info->attrs[NL80211_ATTR_IE])
ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
else
ie_len = 0;
- if (ie_len > wiphy->max_scan_ie_len)
- return -EINVAL;
+ if (ie_len > wiphy->max_scan_ie_len) {
+ err = -EINVAL;
+ goto unlock;
+ }
request = kzalloc(sizeof(*request)
+ sizeof(*request->ssids) * n_ssids
+ sizeof(*request->channels) * n_channels
+ ie_len, GFP_KERNEL);
- if (!request)
- return -ENOMEM;
+ if (!request) {
+ err = -ENOMEM;
+ goto unlock;
+ }
if (n_ssids)
request->ssids = (void *)&request->channels[n_channels];
@@ -4876,6 +4887,8 @@
kfree(request);
}
+ unlock:
+ mutex_unlock(&rdev->sched_scan_mtx);
return err;
}
@@ -7749,20 +7762,9 @@
if (!rdev->ops->stop_p2p_device)
return -EOPNOTSUPP;
- if (!wdev->p2p_started)
- return 0;
-
- rdev_stop_p2p_device(rdev, wdev);
- wdev->p2p_started = false;
-
- mutex_lock(&rdev->devlist_mtx);
- rdev->opencount--;
- mutex_unlock(&rdev->devlist_mtx);
-
- if (WARN_ON(rdev->scan_req && rdev->scan_req->wdev == wdev)) {
- rdev->scan_req->aborted = true;
- ___cfg80211_scan_done(rdev, true);
- }
+ mutex_lock(&rdev->sched_scan_mtx);
+ cfg80211_stop_p2p_device(rdev, wdev);
+ mutex_unlock(&rdev->sched_scan_mtx);
return 0;
}
@@ -8486,7 +8488,7 @@
struct nlattr *nest;
int i;
- ASSERT_RDEV_LOCK(rdev);
+ lockdep_assert_held(&rdev->sched_scan_mtx);
if (WARN_ON(!req))
return 0;
