From: Xie He <xie.he.0141@gmail.com>
To: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Cc: khc@pm.waw.pl, davem@davemloft.net, kuba@kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drivers/net/wan/hdlc_fr: Fix a double free in pvc_xmit
Date: Sun, 2 May 2021 23:06:22 -0700 [thread overview]
Message-ID: <20210503060622.27128-1-xie.he.0141@gmail.com> (raw)
In-Reply-To: <20210328075008.4770-1-lyl2019@mail.ustc.edu.cn>
> 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>
> ---
> 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;
> }
>
1. This patch is incorrect. "__skb_pad" will NOT free the skb on failure
when its "free_on_error" parameter is "false".
2. If you think you fix my commit, please CC me so that I can review
your patch.
I have sent another patch to revert this.
prev parent reply other threads:[~2021-05-03 6:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-28 7:50 [PATCH] drivers/net/wan/hdlc_fr: Fix a double free in pvc_xmit Lv Yunlong
2021-03-29 1:20 ` patchwork-bot+netdevbpf
2021-05-03 6:06 ` Xie He [this message]
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