memif: crash on recceiving a bad descriptor

memif: crash on recceiving a bad descriptor

We validate each descriptor via memif_validate_desc_data and set
desc_status to non-zero for the corresponding descriptor when
the descriptor is bad. However, desc_status is not propagated back to
xor_status in memif_validate_desc_data which eventually sets
ptd->xor_status.

Not setting ptd->xor_status causes us to treat all descriptors as
"simple". In that case, when we try to copy also the bad descriptors to
the buffers, it results a crash since desc_data is not set to point
to the correct memory in the descriptor.

The fix is to set xor_status in memif_validate_desc_data such that if
there is a bad descriptor in the frame, "is_simple" is set to false and
we have to selectively copy only the good descriptors to the buffers.

Type: fix

Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: I780f51a42aa0f8745edcddebbe02b2961c183598