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

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

[Zenghui Yu]

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@huawei.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

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

 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

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

[Daniel Vetter]

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@huawei.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

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

[Zenghui Yu]

On 2024/7/29 15:01, Daniel Vetter wrote:
> 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@huawei.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?

Sure, I can send a patch for that today.

Thanks,
Zenghui