[Mesa-stable] [PATCH] st/clover: Don't segfault on clCreateBuffer with null context

[Francisco Jerez]

Aaron Watry <awatry at gmail.com> writes:

> I guess I misunderstood that obj() call (my IDE is misbehaving on the
> machine I was doing that work on which limited my ability to easily
> find function definitions outside of the current file).  C++ is pretty
> unfamiliar to me and I guess that I figured that the obj() was some
> alternative typecasting operation related to the typing for ctx not an
> actual function call).  This'll teach me to stay away from C++ for a
> while (again).
>

I see.  Maybe something like the attached patch will help avoid future
misunderstandings?

> The segfault that I was actually encountering ended up being in
> ocl-icd (version in the Ubuntu saucy repo).  When I built that project
> straight from git, the segfault went away (there's been quite a few
> null deref fixes in there since the version that Ubuntu 13.10
> packages).  This was after I had already gone through the memory.cpp
> code and broken my understanding of what it was doing.
>
> FYI: I was attempting to run the create-buffer piglit CL API tests
> (I'm working on a new extension of that for clCreateSubBuffer
> testing).  It was disconcerting that the cl-api-create-buffer program
> segfaulted reliably when encountering the test that attempts to
> clCreateBuffer using a NULL context (line 264 in create-buffer.c).
>
> Sorry for the noise.
>
> --Aaron
>
> On Thu, Apr 3, 2014 at 6:54 PM, Francisco Jerez <currojerez at riseup.net> wrote:
>> Aaron Watry <awatry at gmail.com> writes:
>>
>>> This should fix a segfault in the case that you're not using ocl-icd.
>>>
>>> If you're using ocl-icd, make sure your version is new enough or you'll get
>>> the segfault before you even get to clover.
>>>
>>> The null de-ref seems to have been introduced in 10.1, but earlier versions
>>> have have also been affected in other ways.
>>>
>>
>> NAK.  The obj() function already checks if the pointer is NULL.  Not
>> sure how you're getting a segfault.
>>
>>> CC: "10.1" <mesa-stable at lists.freedesktop.org>
>>>
>>> Signed-off-by: Aaron Watry <awatry at gmail.com>
>>> ---
>>>  src/gallium/state_trackers/clover/api/memory.cpp | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/src/gallium/state_trackers/clover/api/memory.cpp b/src/gallium/state_trackers/clover/api/memory.cpp
>>> index 7ed2191..dad5ad3 100644
>>> --- a/src/gallium/state_trackers/clover/api/memory.cpp
>>> +++ b/src/gallium/state_trackers/clover/api/memory.cpp
>>> @@ -32,6 +32,9 @@ clCreateBuffer(cl_context d_ctx, cl_mem_flags flags, size_t size,
>>>                 void *host_ptr, cl_int *r_errcode) try {
>>>     auto &ctx = obj(d_ctx);
>>>
>>> +   if (d_ctx == NULL)
>>> +        throw error(CL_INVALID_CONTEXT);
>>> +
>>>     if (bool(host_ptr) != bool(flags & (CL_MEM_USE_HOST_PTR |
>>>                                         CL_MEM_COPY_HOST_PTR)))
>>>        throw error(CL_INVALID_HOST_PTR);
>>> --
>>> 1.8.3.2
>>>
>>> _______________________________________________
>>> mesa-stable mailing list
>>> mesa-stable at lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/mesa-stable

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