Messages in this thread | | | From | Xie He <> | Subject | Re: [PATCH] drivers/net/wan/hdlc_fr: Fix a double free in pvc_xmit | Date | Sun, 2 May 2021 23:06:22 -0700 |
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> 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.
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