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@ef... Fixes: e46daee53bb5 ("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: Russell King rmk+kernel@armlinux.org.uk CC: stable@vger.kernel.org # v4.14+ CC: linux-arm-kernel@lists.infradead.org CC: patches@armlinux.org.uk --- 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. */