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Subject[PATCH AUTOSEL 5.15 23/42] wifi: mac80211: check skb_shared in ieee80211_8023_xmit()
Date
From: Ryder Lee <ryder.lee@mediatek.com>

[ Upstream commit a4926abb787e2ef3ee2997e6ca8844d859478647 ]

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 <ryder.lee@mediatek.com>
Link: https://lore.kernel.org/r/e7a73aaf7742b17e43421c56625646dfc5c4d2cb.1653571902.git.ryder.lee@mediatek.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 a499b07fee33..717698ff5a37 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2817,19 +2817,10 @@ 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;
@@ -3540,15 +3531,9 @@ 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))
@@ -4438,7 +4423,7 @@ 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;
@@ -4453,6 +4438,11 @@ 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);
--
2.35.1
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