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@xxxxxxxxxx> 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