Re: [5.10, 5.15] New bpf kselftest failure

[Eduard Zingerman <eddyz87@gmail.com>]

On Mon, 2023-07-17 at 09:04 -0400, Luiz Capitulino wrote:
> Hi,
> 
> The upstream commit below is backported to 5.10.186, 5.15.120 and 6.1.36:
> 
> """
> commit ecdf985d7615356b78241fdb159c091830ed0380
> Author: Eduard Zingerman <eddyz87@gmail.com>
> Date:   Wed Feb 15 01:20:27 2023 +0200
> 
>      bpf: track immediate values written to stack by BPF_ST instruction
> """
> 
> This commit is causing the following bpf:test_verifier kselftest to fail:
> 
> """
> # #760/p precise: ST insn causing spi > allocated_stack FAIL
> """
> 

I can reproduce the error on 6.1.36 but don't understand what's causing it yet.
The log is suspiciously different from master, will comment later today.

> Since this test didn't fail before ecdf985d76 backport, the question is
> if this is a test bug or if this commit introduced a regression.
> 
> I haven't checked if this failure is present in latest Linus tree because
> I was unable to build & run the bpf kselftests in an older distro.
> 
> Also, there some important details about running the bpf kselftests
> in 5.10 and 5.15:
> 
> * On 5.10, bpf kselftest build is broken. The following upstream
> commit needs to be cherry-picked for it to build & run:
> 
> """
> commit 4237e9f4a96228ccc8a7abe5e4b30834323cd353
> Author: Gilad Reti <gilad.reti@gmail.com>
> Date:   Wed Jan 13 07:38:08 2021 +0200
> 
>      selftests/bpf: Add verifier test for PTR_TO_MEM spill
> """
> 
> * On 5.15.120 there's one additional test that's failing, but I didn't
> debug this one:
> 
> """
> #150/p calls: trigger reg2btf_ids[reg→type] for reg→type > __BPF_REG_TYPE_MAX FAIL
> FAIL
> """
> 
> * On 5.11 onwards, building and running bpf tests is disabled by
> default by commit 7a6eb7c34a78498742b5f82543b7a68c1c443329, so I wonder
> if we want to backport this to 5.10 as well?
> 
> Thanks!
> 
> - Luiz
>