diff mbox series

[3/3] iwlwifi: mvm: fix a use-after-free bug in iwl_mvm_tx_tso_segment

Message ID 20190723143803.8698-4-johannes@sipsolutions.net (mailing list archive)
State Accepted
Delegated to: Luca Coelho
Headers show
Series iwlwifi: more fixes for 5.3 | expand

Commit Message

Johannes Berg July 23, 2019, 2:38 p.m. UTC 
From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

Accessing the hdr of an skb that was consumed already isn't
a good idea.
First ask if the skb is a QoS packet, then keep that data
on stack, and then consume the skb.
This was spotted by KASAN.

Fixes: 08f7d8b69aaf ("iwlwifi: mvm: bring back mvm GSO code")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 drivers/net/wireless/intel/iwlwifi/mvm/tx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tx.c b/drivers/net/wireless/intel/iwlwifi/mvm/tx.c
index a3e5d88f1c07..6ac114a393cc 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/tx.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tx.c
@@ -831,6 +831,7 @@  iwl_mvm_tx_tso_segment(struct sk_buff *skb, unsigned int num_subframes,
 	unsigned int tcp_payload_len;
 	unsigned int mss = skb_shinfo(skb)->gso_size;
 	bool ipv4 = (skb->protocol == htons(ETH_P_IP));
+	bool qos = ieee80211_is_data_qos(hdr->frame_control);
 	u16 ip_base_id = ipv4 ? ntohs(ip_hdr(skb)->id) : 0;
 
 	skb_shinfo(skb)->gso_size = num_subframes * mss;
@@ -864,7 +865,7 @@  iwl_mvm_tx_tso_segment(struct sk_buff *skb, unsigned int num_subframes,
 		if (tcp_payload_len > mss) {
 			skb_shinfo(tmp)->gso_size = mss;
 		} else {
-			if (ieee80211_is_data_qos(hdr->frame_control)) {
+			if (qos) {
 				u8 *qc;
 
 				if (ipv4)