[openib-general] [PATCH 4/7] IB/ipath - performance improvements via mmap of queues

[Roland Dreier]

 >  struct ib_uverbs_resize_cq_resp {
 >  	__u32 cqe;
 > +	__u32 reserved;
 > +	__u64 driver_data[0];
 >  };

I don't see any changes related to this in uverbs_cmd.c, and you don't
bump the ABI version.  So as far as I can tell, ib_uverbs_resize_cq()
will silently corrupt the stack on an old libibverbs that passes in a
pointer to a 4-byte response structure.

In general I've resisted putting backwards compatibility stuff into
the kernel side of uverbs, so maybe an ABI bump is the answer in this
case too.

But then I have to do another libibverbs 1.0 release etc., which is
kind of a pain.  So in this case it's probably OK to add a check in
ib_uverbs_resize_cq() for when out_len == 4, and not overflow the
response buffer in that case.

 - R.