Re: [PATCH 1/1] Fix: arm: kprobes: optimized kprobes illegal instruction

[Masami Hiramatsu]

On Tue,  5 Feb 2019 10:37:40 -0500
Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:

> commit e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with
> FORTIFY_SOURCE") introduced a regression in optimized kprobes. It
> triggers "invalid instruction" oopses when using kprobes instrumentation
> through lttng and perf. This commit was introduced in kernel v4.20, and
> has been backported to stable kernels 4.19 and 4.14.
> 
> This crash was also reported by Hongzhi Song on the redhat bugzilla
> where the patch was originally introduced.

Thank you for fixing this.

Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>


> 
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1639397
> Link: https://bugs.lttng.org/issues/1174
> Link: https://lore.kernel.org/lkml/342740659.2887.1549307721609.JavaMail.zimbra@xxxxxxxxxxxx
> Fixes: e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE")
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> Reported-by: Robert Berger <Robert.Berger@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Tested-by: Robert Berger <Robert.Berger@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
> CC: Robert Berger <Robert.Berger@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> CC: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> CC: William Cohen <wcohen@xxxxxxxxxx>
> CC: Laura Abbott <labbott@xxxxxxxxxx>
> CC: Kees Cook <keescook@xxxxxxxxxxxx>
> CC: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> CC: <stable@xxxxxxxxxxxxxxx> # v4.14+
> CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> CC: patches@xxxxxxxxxxxxxxx
> ---
> KernelVersion: 5.0.0-rc5
>  arch/arm/probes/kprobes/opt-arm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/probes/kprobes/opt-arm.c b/arch/arm/probes/kprobes/opt-arm.c
> index 2c118a6ab358..0dc23fc227ed 100644
> --- a/arch/arm/probes/kprobes/opt-arm.c
> +++ b/arch/arm/probes/kprobes/opt-arm.c
> @@ -247,7 +247,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *or
>  	}
>  
>  	/* Copy arch-dep-instance from template. */
> -	memcpy(code, (unsigned char *)optprobe_template_entry,
> +	memcpy(code, (unsigned long *)&optprobe_template_entry,
>  			TMPL_END_IDX * sizeof(kprobe_opcode_t));
>  
>  	/* Adjust buffer according to instruction. */
> -- 
> 2.11.0
> 


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>