On Mon, Jan 22, 2024 at 1:47 PM Ilya Maximets <[email protected]> wrote:
>
> On 1/22/24 18:51, Mike Pattrick wrote:
> > The OVN test suite identified a bug in dp_packet_ol_send_prepare() where
> > a double encapsulated BFD packet would trigger a seg fault. This
> > happened because we had assumed that if IP checksumming was marked as
> > offloaded, that checksum would occur in the innermost packet.
> >
> > This change will check that the inner packet has an L3 and L4 before
> > checksumming those parts. And if missing, will resume checksumming the
> > outer components.
>
> Hrm. This looks like a workaround rather than a fix. If the inner packet
> doesn't have L3 header, dp-packet must not have a flag for L3 checksumming
> set in the first place. And if it does have inner L3, the offset must be
> initialized. I guess, some of the offsets can be not initialized, because
> the packet is never parsed by either miniflow_extract() or parse_tcp_flags().
> And the bfd_put_packet() doesn't seem to set them.
I think you're right, I stepped through the problem in GDB and it was
clear that the flags weren't getting reset properly between BFD
packets. I'll send an updated patch.
> BTW, is there actually a double encapsulation in the original OVN test?
> Sounds strange.
The problem was exposed in netdev_push_header() in
dp_packet_ol_send_prepare(packet, 0);
-M
>
> >
> > Fixes: 8b5fe2dc6080 ("userspace: Add Generic Segmentation Offloading.")
> > Reported-by: Dumitru Ceara <[email protected]>
> > Reported-at: https://issues.redhat.com/browse/FDP-300
> > Signed-off-by: Mike Pattrick <[email protected]>
> > ---
> > lib/dp-packet.h | 10 ++++++++--
> > lib/packets.c | 6 +++---
> > 2 files changed, 11 insertions(+), 5 deletions(-)
>
> Best regards, Ilya Maximets.
>
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