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

[PATCH] 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.

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
 tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
index 5f541522364f..2fcc74998fa9 100644
--- a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
+++ b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
@@ -32,6 +32,8 @@ static int check_vgem(int fd)
 	if (ret)
 		return 0;
 
+	name[4] = '\0';
+
 	return !strcmp(name, "vgem");
 }
 
-- 
2.33.0

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

[T.J. Mercier]

On Mon, Jul 8, 2024 at 6:47 AM Zenghui Yu <yuzenghui@huawei.com> 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.

Hm yeah. Looks like drm_copy_field resets version.name to the actual
size of the name in the case of truncation, so maybe worth checking
that too in case there is a name like "vgemfoo" that gets converted to
"vgem\0" by this?

>
> Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
> ---
>  tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> index 5f541522364f..2fcc74998fa9 100644
> --- a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> +++ b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
> @@ -32,6 +32,8 @@ static int check_vgem(int fd)
>         if (ret)
>                 return 0;
>
> +       name[4] = '\0';
> +
>         return !strcmp(name, "vgem");
>  }
>
> --
> 2.33.0
>

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

[Zenghui Yu]

On 2024/7/9 1:49, T.J. Mercier wrote:
> On Mon, Jul 8, 2024 at 6:47 AM Zenghui Yu <yuzenghui@huawei.com> 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.
> 
> Hm yeah. Looks like drm_copy_field resets version.name to the actual
> size of the name in the case of truncation, so maybe worth checking
> that too in case there is a name like "vgemfoo" that gets converted to
> "vgem\0" by this?

Given that drm_copy_field() would set version.name_len to the exact
length of the driver name, this can be addressed by

diff --git a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c 
b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
index 2fcc74998fa9..5d0a809dc2df 100644
--- a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
+++ b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c
@@ -29,7 +29,7 @@ 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';

on top of this patch. What do you think?

Thanks,
Zenghui