From 4cdbf16ba8831de5b3db655032fc3f72423b8d18 Mon Sep 17 00:00:00 2001
From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Date: Mon, 26 Apr 2021 09:06:25 -0700
Subject: [PATCH 3/4] net:emac/emac-mac: Fix a use after free in
emac_mac_tx_buf_send
Git-commit: 6d72e7c767acbbdd44ebc7d89c6690b405b32b57
Patch-mainline: v5.13-rc1
References: git-fixes
In emac_mac_tx_buf_send, it calls emac_tx_fill_tpd(..,skb,..).
If some error happens in emac_tx_fill_tpd(), the skb will be freed via
dev_kfree_skb(skb) in error branch of emac_tx_fill_tpd().
But the freed skb is still used via skb->len by netdev_sent_queue(,skb->len).
As i observed that emac_tx_fill_tpd() haven't modified the value of skb->len,
thus my patch assigns skb->len to 'len' before the possible free and
use 'len' instead of skb->len later.
Fixes: b9b17debc69d2 ("net: emac: emac gigabit ethernet controller driver")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
drivers/net/ethernet/qualcomm/emac/emac-mac.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/qualcomm/emac/emac-mac.c b/drivers/net/ethernet/qualcomm/emac/emac-mac.c
index 97f18cdc9516..7715a0d4b28b 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac-mac.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac-mac.c
@@ -1431,6 +1431,7 @@ int emac_mac_tx_buf_send(struct emac_adapter *adpt, struct emac_tx_queue *tx_q,
{
struct emac_tpd tpd;
u32 prod_idx;
+ int len;
memset(&tpd, 0, sizeof(tpd));
@@ -1450,9 +1451,10 @@ int emac_mac_tx_buf_send(struct emac_adapter *adpt, struct emac_tx_queue *tx_q,
if (skb_network_offset(skb) != ETH_HLEN)
TPD_TYP_SET(&tpd, 1);
+ len = skb->len;
emac_tx_fill_tpd(adpt, tx_q, skb, &tpd);
- netdev_sent_queue(adpt->netdev, skb->len);
+ netdev_sent_queue(adpt->netdev, len);
/* Make sure the are enough free descriptors to hold one
* maximum-sized SKB. We need one desc for each fragment,
--
2.16.4