mac80211: fix A-MSDU packet handling with TCP retransmission
Improves local TCP throughput and fixes use-after-free bugs that could lead to crashes. Signed-off-by: Felix Fietkau <nbd@nbd.name>
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		| @@ -0,0 +1,31 @@ | |||||||
|  | From: Sara Sharon <sara.sharon@intel.com> | ||||||
|  | Date: Thu, 11 Oct 2018 14:21:21 +0200 | ||||||
|  | Subject: [PATCH] mac80211: free skb fraglist before freeing the skb | ||||||
|  |  | ||||||
|  | mac80211 uses the frag list to build AMSDU. When freeing | ||||||
|  | the skb, it may not be really freed, since someone is still | ||||||
|  | holding a reference to it. | ||||||
|  | In that case, when TCP skb is being retransmitted, the | ||||||
|  | pointer to the frag list is being reused, while the data | ||||||
|  | in there is no longer valid. | ||||||
|  | Since we will never get frag list from the network stack, | ||||||
|  | as mac80211 doesn't advertise the capability, we can safely | ||||||
|  | free and nullify it before releasing the SKB. | ||||||
|  |  | ||||||
|  | Signed-off-by: Sara Sharon <sara.sharon@intel.com> | ||||||
|  | --- | ||||||
|  |  | ||||||
|  | --- a/net/mac80211/status.c | ||||||
|  | +++ b/net/mac80211/status.c | ||||||
|  | @@ -561,6 +561,11 @@ static void ieee80211_report_used_skb(st | ||||||
|  |  	} | ||||||
|  |   | ||||||
|  |  	ieee80211_led_tx(local); | ||||||
|  | + | ||||||
|  | +	if (skb_has_frag_list(skb)) { | ||||||
|  | +		kfree_skb_list(skb_shinfo(skb)->frag_list); | ||||||
|  | +		skb_shinfo(skb)->frag_list = NULL; | ||||||
|  | +	} | ||||||
|  |  } | ||||||
|  |   | ||||||
|  |  /* | ||||||
| @@ -96,7 +96,7 @@ Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com> | |||||||
|  	struct rcu_head rcu_head; |  	struct rcu_head rcu_head; | ||||||
| --- a/net/mac80211/status.c | --- a/net/mac80211/status.c | ||||||
| +++ b/net/mac80211/status.c | +++ b/net/mac80211/status.c | ||||||
| @@ -653,9 +653,22 @@ void ieee80211_tx_monitor(struct ieee802 | @@ -658,9 +658,22 @@ void ieee80211_tx_monitor(struct ieee802 | ||||||
|  	struct sk_buff *skb2; |  	struct sk_buff *skb2; | ||||||
|  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); | ||||||
|  	struct ieee80211_sub_if_data *sdata; |  	struct ieee80211_sub_if_data *sdata; | ||||||
|   | |||||||
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