Re: [PATCH net v2 1/1] benet: fix return value check in be_lancer_xmit_workarounds()

[Alexander H Duyck <alexander.duyck@gmail.com>]

On Tue, 2023-07-25 at 11:27 +0800, Yuanjun Gong wrote:
> in be_lancer_xmit_workarounds(), it should go to label 'tx_drop'
> if an unexpected value is returned by pskb_trim().
> 
> Fixes: 93040ae5cc8d ("be2net: Fix to trim skb for padded vlan packets to workaround an ASIC Bug")
> Signed-off-by: Yuanjun Gong <ruc_gongyuanjun@163.com>
> ---
>  drivers/net/ethernet/emulex/benet/be_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
> index 18c2fc880d09..0616b5fe241c 100644
> --- a/drivers/net/ethernet/emulex/benet/be_main.c
> +++ b/drivers/net/ethernet/emulex/benet/be_main.c
> @@ -1138,7 +1138,8 @@ static struct sk_buff *be_lancer_xmit_workarounds(struct be_adapter *adapter,
>  	    (lancer_chip(adapter) || BE3_chip(adapter) ||
>  	     skb_vlan_tag_present(skb)) && is_ipv4_pkt(skb)) {
>  		ip = (struct iphdr *)ip_hdr(skb);
> -		pskb_trim(skb, eth_hdr_len + ntohs(ip->tot_len));
> +		if (unlikely(pskb_trim(skb, eth_hdr_len + ntohs(ip->tot_len))))
> +			goto tx_drop;
>  	}
>  
>  	/* If vlan tag is already inlined in the packet, skip HW VLAN

I'm not sure dropping the packet is the right solution here. Based on
the description of the issue that this is a workaround for it might
make more sense to simply put out a WARN based on the failure since it
means that the tot_len field in the IP header will be modified
incorrectly and a bad IPv4 checksum will be inserted.