diff options
| author | Johannes Berg | 2022-02-01 14:09:51 +0100 |
|---|---|---|
| committer | Johannes Berg | 2022-02-04 16:31:44 +0100 |
| commit | f0a6fd1527067da537e9c48390237488719948ed (patch) | |
| tree | 8a97d6f5056f2affebf3888bdb47f14921366d3c /net/wireless | |
| parent | 5f06f6bf8d816578c390a2b8a485d40adcca4749 (diff) | |
cfg80211: fix race in netlink owner interface destruction
My previous fix here to fix the deadlock left a race where
the exact same deadlock (see the original commit referenced
below) can still happen if cfg80211_destroy_ifaces() already
runs while nl80211_netlink_notify() is still marking some
interfaces as nl_owner_dead.
The race happens because we have two loops here - first we
dev_close() all the netdevs, and then we destroy them. If we
also have two netdevs (first one need only be a wdev though)
then we can find one during the first iteration, close it,
and go to the second iteration -- but then find two, and try
to destroy also the one we didn't close yet.
Fix this by only iterating once.
Reported-by: Toke Høiland-Jørgensen <toke@redhat.com>
Fixes: ea6b2098dd02 ("cfg80211: fix locking in netlink owner interface destruction")
Tested-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20220201130951.22093-1-johannes@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net/wireless')
| -rw-r--r-- | net/wireless/core.c | 17 |
1 files changed, 4 insertions, 13 deletions
diff --git a/net/wireless/core.c b/net/wireless/core.c index 3a54c8e6b6c6..f08d4b3bb148 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -5,7 +5,7 @@ * Copyright 2006-2010 Johannes Berg <johannes@sipsolutions.net> * Copyright 2013-2014 Intel Mobile Communications GmbH * Copyright 2015-2017 Intel Deutschland GmbH - * Copyright (C) 2018-2021 Intel Corporation + * Copyright (C) 2018-2022 Intel Corporation */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt @@ -332,29 +332,20 @@ static void cfg80211_event_work(struct work_struct *work) void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev) { struct wireless_dev *wdev, *tmp; - bool found = false; ASSERT_RTNL(); - list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) { + list_for_each_entry_safe(wdev, tmp, &rdev->wiphy.wdev_list, list) { if (wdev->nl_owner_dead) { if (wdev->netdev) dev_close(wdev->netdev); - found = true; - } - } - - if (!found) - return; - wiphy_lock(&rdev->wiphy); - list_for_each_entry_safe(wdev, tmp, &rdev->wiphy.wdev_list, list) { - if (wdev->nl_owner_dead) { + wiphy_lock(&rdev->wiphy); cfg80211_leave(rdev, wdev); rdev_del_virtual_intf(rdev, wdev); + wiphy_unlock(&rdev->wiphy); } } - wiphy_unlock(&rdev->wiphy); } static void cfg80211_destroy_iface_wk(struct work_struct *work) |