Re: Re: Re: [PATCH] RDMA/siw: Fix compiler warnings on 32-bit due to u64/pointer abuse

Jason Gunthorpe
2019-08-19T14:18:58Z

On Mon, Aug 19, 2019 at 02:15:36PM +0000, Bernard Metzler wrote:
>
> >To: "Bernard Metzler" <BMT@zurich.ibm.com>
> >From: "Jason Gunthorpe" <jgg@ziepe.ca>
> >Date: 08/19/2019 03:52PM
> >Cc: "Geert Uytterhoeven" <geert@linux-m68k.org>, "Doug Ledford"
> ><dledford@redhat.com>, linux-rdma@vger.kernel.org,
> >linux-kernel@vger.kernel.org
> >Subject: [EXTERNAL] Re: Re: [PATCH] RDMA/siw: Fix compiler warnings
> >on 32-bit due to u64/pointer abuse
> >
> >On Mon, Aug 19, 2019 at 01:36:11PM +0000, Bernard Metzler wrote:
> >> >If the value is really a kernel pointer, then it ought to be
> >printed
> >> >with %p. We have been getting demanding on this point lately in
> >RDMA
> >> >to enforce the ability to keep kernel pointers secret.
> >> >
> >> >> - wqe->sqe.sge[0].laddr = (u64)&wqe->sqe.sge[1];
> >> >> + wqe->sqe.sge[0].laddr = (uintptr_t)&wqe->sqe.sge[1];
> >> >
> >> >[..]
> >> >
> >> >> rv = siw_rx_kva(srx,
> >> >> - (void *)(sge->laddr + frx->sge_off),
> >> >> + (void *)(uintptr_t)(sge->laddr + frx->sge_off),
> >> >> sge_bytes);
> >> >
> >> >Bernard, this is nonsense, what is going on here with sge->laddr
> >that
> >> >it can't be a void *?
> >> >
> >> siw_sge is defined in siw-abi.h. We make the address u64 to keep
> >the ABI
> >> arch independent.
> >
> >Eh? How does the siw-abi.h store a kernel pointer? Sounds like kernel
> >and user types are being mixed.
> >
>
> siw-abi.h defines the work queue elements of a siw send queue.
> For user land, the send queue is mmapped. Kernel or user land
> clients write to its send queue when posting work
> (SGE: buffer address, length, local key).

Should have different types.. Don't want to accidently mix a laddr
under user control with one under kernel control.

Jason