Re: test_kmod.sh fails with constant blinding

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On Mon, Jul 4, 2022 at 10:22 AM Yauheni Kaliuta <ykaliuta@xxxxxxxxxx> wrote:
>
> Hi!
>
> On Fri, Jul 1, 2022 at 2:05 PM Yauheni Kaliuta <ykaliuta@xxxxxxxxxx> wrote:
> > >>>>> On Thu, 30 Jun 2022 22:57:37 +0200, Daniel Borkmann  wrote:
> >
> >  > On 6/30/22 3:19 PM, Yauheni Kaliuta wrote:
> >  >> Hi!
> >  >> test_kmod.sh fails for hardened 2 check with
> >  >> test_bpf: #964 Staggered jumps: JMP_JA FAIL to select_runtime
> >  >> err=-524
> >  >> (-ERANGE during constant blinding)
> >  >> Did I miss something?
> >
> >  > That could be expected if one of bpf_adj_delta_to_imm() / bpf_adj_delta_to_off()
> >  > fails given the targets go out of range.
> >
> > I believe that, but how to fix the test? It should not fail.
> >
> >  > How do the generated insn look?
> >
> > The instruction when it fails is
> >
> > (gdb) p/x insn[0]
> > $8 = {code = 0xb7, dst_reg = 0x0, src_reg = 0x0, off = 0x0, imm = 0x2aaa}
> >
> > And it's rewritten as
> >
> > (gdb) p rewritten
> > $9 = 3
> > (gdb) p/x insn_buff[0]
> > $10 = {code = 0xb7, dst_reg = 0xb, src_reg = 0x0, off = 0x0, imm = 0x68ad0283}
> > (gdb) p/x insn_buff[1]
> > $11 = {code = 0xa7, dst_reg = 0xb, src_reg = 0x0, off = 0x0, imm = 0x68ad2829}
> > (gdb) p/x insn_buff[2]
> > $12 = {code = 0xbf, dst_reg = 0x0, src_reg = 0xb, off = 0x0, imm = 0x0}
> >
> > IIUC.
> >
>
> Johan, what do you think?

Hmm, I can take a look at it. What is the target arch?

Johan



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