ARM: 8834/1: Fix: kprobes: optimized kprobes illegal instruction

commit 0ac569bf6a7983c0c5747d6df8db9dc05bc92b6c upstream.

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.

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@efficios.com

Fixes: e46daee53bb5 ("ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE")
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reported-by: NRobert Berger <Robert.Berger@ReliableEmbeddedSystems.com>
Tested-by: NRobert Berger <Robert.Berger@ReliableEmbeddedSystems.com>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: Robert Berger <Robert.Berger@ReliableEmbeddedSystems.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: William Cohen <wcohen@redhat.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org> # v4.14+
Cc: linux-arm-kernel@lists.infradead.org
Cc: patches@armlinux.org.uk
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

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. */