Messages in this thread | | | Date | Wed, 14 Oct 2020 19:54:10 +0300 | From | Vladimir Oltean <> | Subject | Re: [PATCH net] net: dsa: ksz: fix padding size of skb |
| |
On Wed, Oct 14, 2020 at 07:47:50PM +0300, Vladimir Oltean wrote: > On Wed, Oct 14, 2020 at 06:17:19PM +0200, Christian Eggers wrote: > > __skb_put_padto() is called in order to ensure a minimal size of the > > sk_buff. The required minimal size is ETH_ZLEN + the size required for > > the tail tag. > > > > The current argument misses the size for the tail tag. The expression > > "skb->len + padlen" can be simplified to ETH_ZLEN. > > > > Too small sk_buffs typically result from cloning in > > dsa_skb_tx_timestamp(). The cloned sk_buff may not meet the minimum size > > requirements. > > > > Fixes: e71cb9e00922 ("net: dsa: ksz: fix skb freeing") > > Signed-off-by: Christian Eggers <ceggers@arri.de> > > --- > > Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Actually no, I take that back.
This statement:
> The expression "skb->len + padlen" can be simplified to ETH_ZLEN.
is false. skb->len + padlen == ETH_ZLEN only if skb->len is less than ETH_ZLEN. Otherwise, skb->len + padlen == skb->len.
Otherwise said, the frame must be padded to max(skb->len, ETH_ZLEN) + tail tag length.
So please keep the "skb->len + padlen + len".
Thanks, -Vladimir
| |