linux-kernel - Re: [PATCH v2] kselftests: dmabuf-heaps: Ensure the driver name is null-terminated

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Message-ID: <Zqc-ZWlTYwnKHoQK@phenom.ffwll.local>
Date: Mon, 29 Jul 2024 09:01:57 +0200
From: Daniel Vetter <daniel.vetter@...ll.ch>
To: Zenghui Yu <yuzenghui@...wei.com>
Cc: linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linaro-mm-sig@...ts.linaro.org, linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org, sumit.semwal@...aro.org,
	benjamin.gaignard@...labora.com, Brian.Starkey@....com,
	jstultz@...gle.com, tjmercier@...gle.com, shuah@...nel.org,
	wanghaibin.wang@...wei.com
Subject: Re: [PATCH v2] kselftests: dmabuf-heaps: Ensure the driver name is
 null-terminated

On Mon, Jul 29, 2024 at 10:46:04AM +0800, Zenghui Yu wrote:
> Even if a vgem device is configured in, we will skip the import_vgem_fd()
> test almost every time.
> 
>   TAP version 13
>   1..11
>   # Testing heap: system
>   # =======================================
>   # Testing allocation and importing:
>   ok 1 # SKIP Could not open vgem -1
> 
> The problem is that we use the DRM_IOCTL_VERSION ioctl to query the driver
> version information but leave the name field a non-null-terminated string.
> Terminate it properly to actually test against the vgem device.
> 
> While at it, let's check the length of the driver name is exactly 4 bytes
> and return early otherwise (in case there is a name like "vgemfoo" that
> gets converted to "vgem\0" unexpectedly).
> 
> Signed-off-by: Zenghui Yu <yuzenghui@...wei.com>
> ---
> * From v1 [1]:
>   - Check version.name_len is exactly 4 bytes and return early otherwise
> 
> [1] https://lore.kernel.org/r/20240708134654.1725-1-yuzenghui@huawei.com

Thanks for your patch, I'll push it to drm-misc-next-fixes.

> P.S., Maybe worth including the kselftests file into "DMA-BUF HEAPS
> FRAMEWORK" MAINTAINERS entry?

Good idea, want to do the patch for that too?

Cheers, Sima


> 
>  tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> index 5f541522364f..5d0a809dc2df 100644
> --- a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> +++ b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> @@ -29,9 +29,11 @@ static int check_vgem(int fd)
>  	version.name = name;
>  
>  	ret = ioctl(fd, DRM_IOCTL_VERSION, &version);
> -	if (ret)
> +	if (ret || version.name_len != 4)
>  		return 0;
>  
> +	name[4] = '\0';
> +
>  	return !strcmp(name, "vgem");
>  }
>  
> -- 
> 2.33.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch