Re: test_kmod.sh fails with constant blinding

[Yauheni Kaliuta <ykaliuta@redhat.com>]

Hi, Johan!

>>>>> On Tue, 5 Jul 2022 11:31:58 +0300, Yauheni Kaliuta  wrote:

 > Hi, Johan!
 > On Tue, Jul 5, 2022 at 11:06 AM Johan Almbladh
 > <johan.almbladh@anyfinetworks.com> wrote:
 >> 
 >> On Mon, Jul 4, 2022 at 10:22 AM Yauheni Kaliuta <ykaliuta@redhat.com> wrote:
 >> >
 >> > Hi!
 >> >
 >> > On Fri, Jul 1, 2022 at 2:05 PM Yauheni Kaliuta <ykaliuta@redhat.com> 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?
 >> 

 > It fails even on x86.

Did you have a chance to look?

-- 
WBR,
Yauheni Kaliuta