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

compudj · Russell King · commit 0ac569bf6a79 · 2019-02-12T15:20:58.000Z
commit e46daee ("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: e46daee ("ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reported-by: Robert Berger <Robert.Berger@ReliableEmbeddedSystems.com> Tested-by: Robert Berger <Robert.Berger@ReliableEmbeddedSystems.com> Acked-by: Kees 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: Russell King <rmk+kernel@armlinux.org.uk>
diff --git 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. */

Original file line number	Diff line number	Diff line change
`@@ -247,7 +247,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe op, struct kprobe or`
`247`	`247`	`}`
`248`	`248`
`249`	`249`	`/* Copy arch-dep-instance from template. */`
`250`		`- memcpy(code, (unsigned char *)optprobe_template_entry,`
	`250`	`+ memcpy(code, (unsigned long *)&optprobe_template_entry,`
`251`	`251`	`TMPL_END_IDX * sizeof(kprobe_opcode_t));`
`252`	`252`
`253`	`253`	`/* Adjust buffer according to instruction. */`