2019-04-16 07:25:09

by Bhagavathi Perumal S

Subject: [PATCH] mac80211: Fix kernel panic due to use of txq after free

The txq of vif is added to active_txqs list for ATF TXQ scheduling
in the function ieee80211_queue_skb(), but it was not properly removed
before freeing the txq object. It was causing use after free of the txq
objects from the active_txqs list, result was kernel panic
due to invalid memory access.

Fix kernel invalid memory access by properly removing txq object
from active_txqs list before free the object.

Signed-off-by: Bhagavathi Perumal S <[email protected]>
---
net/mac80211/iface.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 94459b2..410685d 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1907,6 +1907,9 @@ void ieee80211_if_remove(struct ieee80211_sub_if_data *sdata)
list_del_rcu(&sdata->list);
mutex_unlock(&sdata->local->iflist_mtx);

+ if (sdata->vif.txq)
+ ieee80211_txq_purge(sdata->local, to_txq_info(sdata->vif.txq));
+
synchronize_rcu();

if (sdata->dev) {
--
1.9.1

2019-04-16 08:49:15

by Toke Høiland-Jørgensen

Subject: Re: [PATCH] mac80211: Fix kernel panic due to use of txq after free

Bhagavathi Perumal S <[email protected]> writes:

> The txq of vif is added to active_txqs list for ATF TXQ scheduling
> in the function ieee80211_queue_skb(), but it was not properly removed
> before freeing the txq object. It was causing use after free of the txq
> objects from the active_txqs list, result was kernel panic
> due to invalid memory access.
>
> Fix kernel invalid memory access by properly removing txq object
> from active_txqs list before free the object.
>
> Signed-off-by: Bhagavathi Perumal S <[email protected]>

Nice catch, thanks!

Acked-by: Toke Høiland-Jørgensen <[email protected]>

This should probably have a fixes tag:

Fixes: 1866760096bf ("mac80211: Add TXQ scheduling API")

-Toke