[BUG] null pointer dereference when loading bpf_preload on Raspberry Pi

[Peter Robinson]

Hi Stefan,

> >>> Jan Palus already reported this NULL pointer dereference on bugzilla
> >>> [1], but i want to make sure this is noticed by the right people.
> >>>
> >>> I've i boot my Raspberry Pi 3 B Plus with multi_v7_defconfig and the
> >>> following config settings:
> >>>
> >>> CONFIG_BPF_SYSCALL=y
> >>> CONFIG_BPF_JIT=y
> >>> CONFIG_BPF_JIT_ALWAYS_ON=y
> >>> CONFIG_BPF_JIT_DEFAULT_ON=y
> >>> CONFIG_BPF_UNPRIV_DEFAULT_OFF=y
> >>> CONFIG_USERMODE_DRIVER=y
> >>> CONFIG_BPF_PRELOAD=y
> >>> CONFIG_BPF_PRELOAD_UMD=m
> >> are you able to see this issue in 5.18.x, too? I'm asking because the
> >> BPF settings comes from your configuration.
> > I've not seen it in a standard boot, is there a simple way to test
> > this, TBH I've never really played with bpf (it's on the todo list) so
> > if there's an easy test I can certainly check.
>
> it's just during boot. No need to do something special.
>
> I want to figure out, if this is caused by my cross compile environment.

No, not seeing that anywhere, I've got 5.18.3 running on omap/rpi/imx6
32 bit devices without anything like that

We had an issue around BPF on arm32 back in late 2018 and I tried to
turn some of the options on in defconfig so they'd have wider testing
but got push back. I don't remember the exact issue there though (and
it's long been fixed)

Peter