Re: [PATCH] parisc: Avoid kernel panic triggered by invalid kprobe

[Sven Schnelle <svens@stackframe.org>]

Hi Helge,

On Tue, Jul 16, 2019 at 09:16:26PM +0200, Helge Deller wrote:
> When running gdb I was able to trigger this kernel panic:
> [OOps]

> Avoid this panic by checking the return value of kprobe_running() and
> skip kprobe if none is currently active.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> Cc: <stable@vger.kernel.org> # v5.2
> 
> diff --git a/arch/parisc/kernel/kprobes.c b/arch/parisc/kernel/kprobes.c
> index d58960b33bda..0385a8fd74aa 100644
> --- a/arch/parisc/kernel/kprobes.c
> +++ b/arch/parisc/kernel/kprobes.c
> @@ -133,6 +133,9 @@ int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs)
>  	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
>  	struct kprobe *p = kprobe_running();
> 
> +	if (!p)
> +		return 0;
> +
>  	if (regs->iaoq[0] != (unsigned long)p->ainsn.insn+4)
>  		return 0;
> 

Looks ok to me. I assume this happened during single-stepping?

Acked-by: Sven Schnelle <svens@stackframe.org>