[PATCH 5.11 123/210] drivers/net/wan/hdlc_fr: Fix a double free in pvc_xmit

Greg Kroah-Hartman
2021-04-12T09:32:52Z

From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>

[ Upstream commit 1b479fb801602b22512f53c19b1f93a4fc5d5d9d ]

In pvc_xmit, if __skb_pad(skb, pad, false) failed, it will free
the skb in the first time and goto drop. But the same skb is freed
by kfree_skb(skb) in the second time in drop.

Maintaining the original function unchanged, my patch adds a new
label out to avoid the double free if __skb_pad() failed.

Fixes: f5083d0cee08a ("drivers/net/wan/hdlc_fr: Improvements to the code of pvc_xmit")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wan/hdlc_fr.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
index 0720f5f92caa..4d9dc7d15908 100644
--- a/drivers/net/wan/hdlc_fr.c
+++ b/drivers/net/wan/hdlc_fr.c
@@ -415,7 +415,7 @@ static netdev_tx_t pvc_xmit(struct sk_buff *skb, struct net_device *dev)

if (pad > 0) { /* Pad the frame with zeros */
if (__skb_pad(skb, pad, false))
- goto drop;
+ goto out;
skb_put(skb, pad);
}
}
@@ -448,8 +448,9 @@ static netdev_tx_t pvc_xmit(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_OK;

drop:
- dev->stats.tx_dropped++;
kfree_skb(skb);
+out:
+ dev->stats.tx_dropped++;
return NETDEV_TX_OK;
}

--
2.30.2