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

[Toke Høiland-Jørgensen]

Bhagavathi Perumal S  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 

Nice catch, thanks!

Acked-by: Toke Høiland-Jørgensen 

This should probably have a fixes tag:

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

-Toke

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

[Bhagavathi Perumal S]

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 
---
 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(>list);
mutex_unlock(>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


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