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authorJohannes Berg <johannes.berg@intel.com>2022-02-01 14:09:51 +0100
committerJohannes Berg <johannes.berg@intel.com>2022-02-04 16:31:44 +0100
commitf0a6fd1527067da537e9c48390237488719948ed (patch)
tree8a97d6f5056f2affebf3888bdb47f14921366d3c
parent5f06f6bf8d816578c390a2b8a485d40adcca4749 (diff)
downloadlinux-f0a6fd1527067da537e9c48390237488719948ed.tar.bz2
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>
-rw-r--r--net/wireless/core.c17
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)