Re: [PATCHv2 6/6] net: fec: fix regression on i.MX28 introduced by rx_copybreak support

["Lothar Waßmann" <LW@KARO-electronics.de>]

Hi,

David Laight wrote:
> From:  Lothar Waßmann
> > commit 1b7bde6d659d ("net: fec: implement rx_copybreak to improve rx performance")
> > introduced a regression for i.MX28. The swap_buffer() function doing
> > the endian conversion of the received data on i.MX28 may access memory
> > beyond the actual packet size in the DMA buffer. fec_enet_copybreak()
> > does not copy those bytes, so that the last bytes of a packet may be
> > filled with invalid data after swapping.
> > This will likely lead to checksum errors on received packets.
> > E.g. when trying to mount an NFS rootfs:
> > UDP: bad checksum. From 192.168.1.225:111 to 192.168.100.73:44662 ulen 36
> > 
> > Do the byte swapping and copying to the new skb in one go if
> > necessary.
> > 
> > Signed-off-by: Lothar Wamann <LW@KARO-electronics.de>
> > ---
> >  drivers/net/ethernet/freescale/fec_main.c |   25 +++++++++++++++++++++----
> >  1 file changed, 21 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> > index 404fb9d..b92324c 100644
> > --- a/drivers/net/ethernet/freescale/fec_main.c
> > +++ b/drivers/net/ethernet/freescale/fec_main.c
> > @@ -339,6 +339,18 @@ static void *swap_buffer(void *bufaddr, int len)
> >  	return bufaddr;
> >  }
> > 
> > +static void *swap_buffer2(void *dst_buf, void *src_buf, int len)
> > +{
> > +	int i;
> > +	unsigned int *src = src_buf;
> > +	unsigned int *dst = dst_buf;
> > +
> > +	for (i = 0; i < len; i += 4, src++, dst++)
> > +		swab32s(src);
> > +
> > +	return dst_buf;
> > +}
> > +
> 
> Actually that is completely f*cked....
> 
Yeah, noticed that shortly after sending out. :(
One change too many...


Lothar Waßmann