linux-kernel - RE: Re: [PATCH] RDMA/siw: fix pointer cast warning

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Message-ID: <SA0PR15MB3919F3295251A173D0E14C3F99E69@SA0PR15MB3919.namprd15.prod.outlook.com>
Date:   Fri, 16 Dec 2022 10:01:02 +0000
From:   Bernard Metzler <BMT@...ich.ibm.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        David Laight <David.Laight@...lab.com>
CC:     Arnd Bergmann <arnd@...nel.org>, Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: Re: [PATCH] RDMA/siw: fix pointer cast warning



> -----Original Message-----
> From: Linus Walleij <linus.walleij@...aro.org>
> Sent: Friday, 16 December 2022 08:47
> To: David Laight <David.Laight@...lab.com>
> Cc: Arnd Bergmann <arnd@...nel.org>; Bernard Metzler <BMT@...ich.ibm.com>;
> Jason Gunthorpe <jgg@...pe.ca>; Leon Romanovsky <leon@...nel.org>; Arnd
> Bergmann <arnd@...db.de>; linux-rdma@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: [EXTERNAL] Re: [PATCH] RDMA/siw: fix pointer cast warning
> 
> On Thu, Dec 15, 2022 at 11:20 PM David Laight <David.Laight@...lab.com>
> wrote:
> 
> > From: Arnd Bergmann
> > > Sent: 15 December 2022 17:04
> > >
> > > From: Arnd Bergmann <arnd@...db.de>
> > >
> > > The previous build fix left a remaining issue in configurations
> > > with 64-bit dma_addr_t on 32-bit architectures:
> > >
> > > drivers/infiniband/sw/siw/siw_qp_tx.c: In function 'siw_get_pblpage':
> > > drivers/infiniband/sw/siw/siw_qp_tx.c:32:37: error: cast to pointer
> from integer of different size [-
> > > Werror=int-to-pointer-cast]
> > >    32 |                 return virt_to_page((void *)paddr);
> > >       |                                     ^
> > >
> > > Use the same double cast here that the driver uses elsewhere
> > > to convert between dma_addr_t and void*.
> > >
> > > It took me a while to figure out why this driver does it
> > > like this, as there is no hardware access and it just stores
> > > kernel pointers in place of device addresses when communicating
> > > with the rdma core and with user space.
> >
> > I hope that doesn't mean it is relying on user space only
> > giving it back valid values?
> 
> It looks to me like this driver totally trusts userspace.
> 

Shame on me. Yes, somehow, an access_ok((void __user *)start, len)
is missing! Let me fix that when I am back at my desk. Seems it needs
immediate action.

Many thanks for pointing that out!
Bernard.

> Yours,
> Linus Walleij