[PATCH] dma-buf: Fix SET_NAME ioctl uapi

[Sumit Semwal]

Thanks for the patch, Daniel!


On Tue, 7 Apr 2020 at 19:00, Daniel Vetter <daniel.vetter at 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 at linaro.org>
> Cc: Chenbo Feng <fengc at google.com>
> Cc: Greg Hackmann <ghackmann at google.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: linux-media at vger.kernel.org
> Cc: linaro-mm-sig at lists.linaro.org
> Cc: minchan at kernel.org
> Cc: surenb at google.com
> Cc: jenhaochen at google.com
> Cc: Martin Liu <liumartin at 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.

> Signed-off-by: Daniel Vetter <daniel.vetter at 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.