[PATCH] scsi/bnx2fc/bnx2fx_fcore: Fix a double free in bnx2fc_rcv

From: Lv Yunlong
Date: Mon May 24 2021 - 06:23:38 EST

In bnx2fc_rcv, it calls skb_share_check(skb,GFP_ATOMIC) to clone
the skb. But if skb_clone() failed, skb_share_check() will free
the skb in the first time and return NULL. Then skb_share_check()
returns NULL and goto err.

Unfortunately, the same skb is freed in the second time in the err.

As kfree_skb() free a null pointer is a safe operation, my patch
put "skb = tmp_skb;" ahead of the "if(!tmp_skb) goto err;". So that
if skb_share_check() failed, skb will be a null pointer.

Signed-off-by: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx>
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index 8863a74e6c57..89c277cb93b2 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -445,11 +445,10 @@ static int bnx2fc_rcv(struct sk_buff *skb, struct net_device *dev,

tmp_skb = skb_share_check(skb, GFP_ATOMIC);
+ skb = tmp_skb;
if (!tmp_skb)
goto err;

- skb = tmp_skb;
if (unlikely(eth_hdr(skb)->h_proto != htons(ETH_P_FCOE))) {
printk(KERN_ERR PFX "bnx2fc_rcv: Wrong FC type frame\n");
goto err;