On Mon, Feb 4, 2019 at 9:52 PM Mathieu Desnoyers
<[email protected]> 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.
Ew, yes. Thanks for catching this.
Fixes: e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with
FORTIFY_SOURCE")
Acked-by: Kees Cook <[email protected]>
Can you send this to the ARM patch tracker, please?
-Kees
>
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1639397
> Link: https://bugs.lttng.org/issues/1174
> Link:
> https://lore.kernel.org/lkml/[email protected]
> Signed-off-by: Mathieu Desnoyers <[email protected]>
> Reported-by: Robert Berger <[email protected]>
> Tested-by: Robert Berger <[email protected]>
> CC: Robert Berger <[email protected]>
> CC: Masami Hiramatsu <[email protected]>
> CC: William Cohen <[email protected]>
> CC: Laura Abbott <[email protected]>
> CC: Kees Cook <[email protected]>
> CC: Russell King <[email protected]>
> CC: <[email protected]> # v4.14+
> ---
> 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
>
--
Kees Cook
