Re: [PATCH 00/18] prevent bounds-check bypass via speculative execution

Dan Williams
2018-01-09T19:44:07Z

On Tue, Jan 9, 2018 at 11:34 AM, Jiri Kosina <jikos@kernel.org> wrote:
> On Fri, 5 Jan 2018, Dan Williams wrote:
>
> [ ... snip ... ]
>> Andi Kleen (1):
>> x86, barrier: stop speculation for failed access_ok
>>
>> Dan Williams (13):
>> x86: implement nospec_barrier()
>> [media] uvcvideo: prevent bounds-check bypass via speculative execution
>> carl9170: prevent bounds-check bypass via speculative execution
>> p54: prevent bounds-check bypass via speculative execution
>> qla2xxx: prevent bounds-check bypass via speculative execution
>> cw1200: prevent bounds-check bypass via speculative execution
>> Thermal/int340x: prevent bounds-check bypass via speculative execution
>> ipv6: prevent bounds-check bypass via speculative execution
>> ipv4: prevent bounds-check bypass via speculative execution
>> vfs, fdtable: prevent bounds-check bypass via speculative execution
>> net: mpls: prevent bounds-check bypass via speculative execution
>> udf: prevent bounds-check bypass via speculative execution
>> userns: prevent bounds-check bypass via speculative execution
>>
>> Mark Rutland (4):
>> asm-generic/barrier: add generic nospec helpers
>> Documentation: document nospec helpers
>> arm64: implement nospec_ptr()
>> arm: implement nospec_ptr()
>
> So considering the recent publication of [1], how come we all of a sudden
> don't need the barriers in ___bpf_prog_run(), namely for LD_IMM_DW and
> LDX_MEM_##SIZEOP, and something comparable for eBPF JIT?
>
> Is this going to be handled in eBPF in some other way?
>
> Without that in place, and considering Jann Horn's paper, it would seem
> like PTI doesn't really lock it down fully, right?

Here is the latest (v3) bpf fix:

https://patchwork.ozlabs.org/patch/856645/

I currently have v2 on my 'nospec' branch and will move that to v3 for
the next update, unless it goes upstream before then.