On Fri, Oct 16, 2020 at 04:00:36PM +0200, Andrew Lunn wrote: > On Fri, Oct 16, 2020 at 09:35:27AM +0200, Christian Eggers wrote: > > If the supplied sk_buff is cloned (e.g. in dsa_skb_tx_timestamp()), > > __skb_put_padto() will allocate a new sk_buff with size = skb->len + > > padlen. So the condition just tested for (skb_tailroom(skb) >= padlen + > > len) is not fulfilled anymore. Although the real size will usually be > > larger than skb->len + padlen (due to alignment), there is no guarantee > > that the required memory for the tail tag will be available > > > > Instead of letting __skb_put_padto allocate a new (too small) sk_buff, > > lets take the already existing path and allocate a new sk_buff ourself > > (with sufficient size). > > Hi Christian > > What is not clear to me is why not change the __skb_put_padto() call > to pass the correct length?
There is a second call to skb_put that increases the skb->len further from the tailroom area. See Christian's other patch. I would treat this patch as "premature" until we fully understand what's going on there.
