vmgfx gcc-7.1.1 warning..

[Daniel Vetter]

On Thu, Jul 13, 2017 at 10:28 PM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Thu, Jul 13, 2017 at 10:11 PM, Linus Torvalds
> <torvalds at linux-foundation.org> wrote:
>> This one actually seems to imply that vmw_cmd_invalid() is broken:
>>
>> drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:522:34: warning: the omitted
>> middle operand in ?: will always be ‘true’, suggest explicit middle
>> operand [-Wparentheses]
>>   return capable(CAP_SYS_ADMIN) ? : -EINVAL;
>>                                   ^
>>
>> gcc is very right. I think the *intent* of that function is to return
>> 0 if CAP_SYS_ADMIN, but it always returns nonzero.
>>
>> If CAP_SYS_ADMIN is true, it returns 1, and if it's false it returns -EINVAL.
>>
>> Since nobody has noticed in many many years, maybe it should just
>> always return -EINVAL unconditionally?
>
> Fun one. It's the security parser afaict, and it looks like no one
> wrote a testcase to make sure it actually catches the bad guys. Or
> it's not needed, since there's 3 more security checks above it in
> vmw_cmd_check.

Meh got it wrong, it rejects always. Could indeed just be dead code
since forever, no idea why that's there.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch