On Fri, Aug 17, 2018 at 7:30 PM, Daniel Borkmann <dan...@iogearbox.net> wrote:
> On 08/17/2018 06:17 PM, Russell King - ARM Linux wrote:
>> On Fri, Aug 17, 2018 at 02:40:19PM +0200, Daniel Borkmann wrote:
>>> I'd have one potential bug suspicion, for the 4.18 one you were trying,
>>> could you run with the below patch to see whether it would help?
>>
>> I think this is almost certainly the problem - looking at the history,
>> it seems that the "-4" was assumed to be part of the scratch stuff in
>> commit 38ca93060163 ("bpf, arm32: save 4 bytes of unneeded stack space")
>> but it isn't - it's because "off" of zero refers to the top word in the
>> stack (iow at STACK_SIZE-4).
>
> Yeah agree, my thinking as well (albeit bit late, sigh, sorry about that).
> Waiting for Peter to get back with results for definite confirmation. Your
> rework in 1c35ba122d4a ("ARM: net: bpf: use negative numbers for stacked
> registers") and 96cced4e774a ("ARM: net: bpf: access eBPF scratch space using
> ARM FP register") fixes this in mainline, so unless I'm missing something this
> would only need a stand-alone fix for 4.18/stable which I can cook up and
> submit then.I can confirm that fixes the problems I was seeing on Fedora 29. Feel free to add a tested by from me: Tested-by: Peter Robinson <pbrobin...@gmail.com>
