Add a missing skb_shared check into 802.3 path to prevent potential
use-after-free from happening. This also uses skb_share_check()
instead of open-coding in tx path.
Signed-off-by: Ryder Lee <[email protected]>
---
change since v2 - switch to use skb_share_check()
---
net/mac80211/tx.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 0e4efc08c762..c425f4fb7c2e 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2818,19 +2818,10 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
/*
* If the skb is shared we need to obtain our own copy.
*/
- if (skb_shared(skb)) {
- struct sk_buff *tmp_skb = skb;
-
- /* can't happen -- skb is a clone if info_id != 0 */
- WARN_ON(info_id);
-
- skb = skb_clone(skb, GFP_ATOMIC);
- kfree_skb(tmp_skb);
-
- if (!skb) {
- ret = -ENOMEM;
- goto free;
- }
+ skb = skb_share_check(skb, GFP_ATOMIC);
+ if (unlikely(!skb)) {
+ ret = -ENOMEM;
+ goto free;
}
hdr.frame_control = fc;
@@ -3539,15 +3530,9 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
/* after this point (skb is modified) we cannot return false */
- if (skb_shared(skb)) {
- struct sk_buff *tmp_skb = skb;
-
- skb = skb_clone(skb, GFP_ATOMIC);
- kfree_skb(tmp_skb);
-
- if (!skb)
- return true;
- }
+ skb = skb_share_check(skb, GFP_ATOMIC);
+ if (unlikely(!skb))
+ return true;
if ((hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) &&
ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb))
@@ -4437,7 +4422,7 @@ static void ieee80211_8023_xmit(struct ieee80211_sub_if_data *sdata,
struct net_device *dev, struct sta_info *sta,
struct ieee80211_key *key, struct sk_buff *skb)
{
- struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct ieee80211_tx_info *info;
struct ieee80211_local *local = sdata->local;
struct tid_ampdu_tx *tid_tx;
u8 tid;
@@ -4452,6 +4437,11 @@ static void ieee80211_8023_xmit(struct ieee80211_sub_if_data *sdata,
test_bit(SDATA_STATE_OFFCHANNEL, &sdata->state))
goto out_free;
+ skb = skb_share_check(skb, GFP_ATOMIC);
+ if (unlikely(!skb))
+ return;
+
+ info = IEEE80211_SKB_CB(skb);
memset(info, 0, sizeof(*info));
ieee80211_aggr_check(sdata, sta, skb);
--
2.29.2