Re: [PATCH v33 15/21] x86/vdso: Add support for exception fixup in vDSO functions

[Thomas Gleixner]

Andy Lutomirski <luto@xxxxxxxxxxxxxx> writes:
> On Tue, Jun 30, 2020 at 1:41 AM Borislav Petkov <bp@xxxxxxxxx> wrote:
>>
>> On Mon, Jun 29, 2020 at 11:00:55PM -0700, Sean Christopherson wrote:
>> > E.g. the vDSO function should get the fixup even if userspace screws
>> > up mmap() and invokes __vdso_sgx_enter_enclave() without being tagged
>> > an SGX task.
>>
>> I sincerely hope you don't mean this seriously.
>>
>> Please add a member to task_struct which denotes that a task is an
>> sgx task, test that member where needed and forget real quickly about
>> running *any* *fixup* for unrelated tasks.
>
> I don't see the problem.  If you call this magic vDSO function and get
> a fault, it gets handled.  What's the failure mode?

Handled by some definition of handled. If a random user space tasks ends
up in that function then it will not die as it would otherwise, but I
don't see a real issue with that either.

Thanks,

        tglx