[Mesa-stable] [Mesa-dev] [PATCH] anv/entrypoints: VkGetDeviceProcAddr returns NULL for core instance commands

[Emil Velikov]

On 6 March 2018 at 12:26, Iago Toral <itoral at igalia.com> wrote:
> On Tue, 2018-03-06 at 12:16 +0000, Emil Velikov wrote:
>> On 6 March 2018 at 12:09, Iago Toral <itoral at igalia.com> wrote:
>> > On Tue, 2018-03-06 at 11:21 +0000, Emil Velikov wrote:
>> > > On 6 March 2018 at 09:57, Bas Nieuwenhuizen <basni at chromium.org>
>> > > wrote:
>> > > >
>> > > >
>> > > > On Tue, Mar 6, 2018 at 8:02 AM, Iago Toral <itoral at igalia.com>
>> > > > wrote:
>> > > > >
>> > > > > On Mon, 2018-03-05 at 12:11 +0000, Emil Velikov wrote:
>> > > > > > Hi Iago,
>> > > > > >
>> > > > > > Top level questions:
>> > > > > >
>> > > > > > I think this and the original commit should go to stable
>> > > > > > right?
>> > > > >
>> > > > > I am not sure if this qualifies for stable: these patches
>> > > > > don't
>> > > > > fix any
>> > > > > user-visible bugs. If an application was calling
>> > > > > vkGetDeviceProcAddr to
>> > > > > get pointers to non-device functions (which is incorrect by
>> > > > > the
>> > > > > spec)
>> > > > > the previous behavior would allow it to get away with it
>> > > > > without
>> > > > > issues, bit with these patches it will start to crash since
>> > > > > it
>> > > > > will
>> > > > > receive NULL pointers.
>> > > > >
>> > >
>> > > According to Lenny's comment in the github issue there's nothing
>> > > to
>> > > be
>> > > concerned. Namely:
>> > >  - "The pointers being returned are invalid. ... trying to use
>> > > them
>> > > will result in a crash."
>> > >  - "Wolfenstein was acquiring, but not using the pointers."
>> >
>> > Because it is not using the pointers :), if some other app is using
>> > them it will start to crash.
>> >
>> > But that was not my point, my point was that this doesn't fix
>> > anything
>> > for users, so I was questioning whether it was material for stable
>> > based on that.
>> >
>>
>> Surely we don't want to apps be written against the current incorrect
>> behaviour?
>> Which may go unnoticed since there are no validation/loader checks
>> for
>> this (based on the github issue).
>
> If there is such an application, and this patch makes it into the
> stable release, that application will probably start to crash.
Such an application will crash _regardless_ of the patch, as mentioned earlier.
That is as per Lenny's analysis - haven't checked it personally.

-Emil