Re: [PATCH] dma-buf: Fix SET_NAME ioctl uapi

[Martin Liu <liumartin@google.com>]

On Thu, Apr 09, 2020 at 09:28:16AM +0530, Sumit Semwal wrote:
> Thanks for the patch, Daniel!
> 
> 
> On Tue, 7 Apr 2020 at 19:00, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> >
> > The uapi is the same on 32 and 64 bit, but the number isnt. Everyone
> > who botched this please re-read:
> >
> > https://www.kernel.org/doc/html/v5.4-preprc-cpu/ioctl/botching-up-ioctls.html
> >
> > Also, the type argument for the ioctl macros is for the type the void
> > __user *arg pointer points at, which in this case would be the
> > variable-sized char[] of a 0 terminated string. So this was botched in
> > more than just the usual ways.
> 
> Yes, it shouldn't have passed through the cracks; my apologies!
> 
> >
> > Cc: Sumit Semwal <sumit.semwal@linaro.org>
> > Cc: Chenbo Feng <fengc@google.com>
> > Cc: Greg Hackmann <ghackmann@google.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: linux-media@vger.kernel.org
> > Cc: linaro-mm-sig@lists.linaro.org
> > Cc: minchan@kernel.org
> > Cc: surenb@google.com
> > Cc: jenhaochen@google.com
> > Cc: Martin Liu <liumartin@google.com>
> 
> Martin,
> Could I request you to test this one with the 4 combinations of 32-bit
> / 64-bit userspace and kernel, and let us know that all 4 are working
> alright? If yes, please consider giving your tested-by here.
>
Hi Sumit, Daniel,
Sorry for being late to the tests. I finished the tests on 32/64 apps
with 64 bit kernel and they were fine. Unfortunately, I couldn't have a 32
bit kernel to run the tests somehow. However, this should work from the
code logic. Hope this is okay to you and thanks for Todd's help.

Tested-by: Martin Liu <liumartin@google.com>
Reviewed-by: Martin Liu <liumartin@google.com>

> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > ---
> >  drivers/dma-buf/dma-buf.c    | 3 ++-
> >  include/uapi/linux/dma-buf.h | 4 ++++
> >  2 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index 570c923023e6..1d923b8e4c59 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -388,7 +388,8 @@ static long dma_buf_ioctl(struct file *file,
> >
> >                 return ret;
> >
> > -       case DMA_BUF_SET_NAME:
> > +       case DMA_BUF_SET_NAME_A:
> > +       case DMA_BUF_SET_NAME_B:
> >                 return dma_buf_set_name(dmabuf, (const char __user *)arg);
> >
> >         default:
> > diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
> > index dbc7092e04b5..21dfac815dc0 100644
> > --- a/include/uapi/linux/dma-buf.h
> > +++ b/include/uapi/linux/dma-buf.h
> > @@ -39,6 +39,10 @@ struct dma_buf_sync {
> >
> >  #define DMA_BUF_BASE           'b'
> >  #define DMA_BUF_IOCTL_SYNC     _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
> > +/* 32/64bitness of this uapi was botched in android, there's no difference
> > + * between them in actual uapi, they're just different numbers. */
> >  #define DMA_BUF_SET_NAME       _IOW(DMA_BUF_BASE, 1, const char *)
> > +#define DMA_BUF_SET_NAME_A     _IOW(DMA_BUF_BASE, 1, u32)
> > +#define DMA_BUF_SET_NAME_B     _IOW(DMA_BUF_BASE, 1, u64)
> >
> >  #endif
> > --
> > 2.25.1
> >
> Best,
> Sumit.