From: Michael Kelley Date: Thu, 18 May 2017 17:46:07 +0000 (-0700) Subject: Drivers: hv: vmbus: Close timing hole that can corrupt per-cpu page X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=13b9abfc92be7c4454bff912021b9f835dea6e15;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git Drivers: hv: vmbus: Close timing hole that can corrupt per-cpu page Extend the disabling of preemption to include the hypercall so that another thread can't get the CPU and corrupt the per-cpu page used for hypercall arguments. Cc: #4.11 Signed-off-by: Michael Kelley Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index 61fc8ce169a5..2ea12207caa0 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -82,10 +82,15 @@ int hv_post_message(union hv_connection_id connection_id, aligned_msg->message_type = message_type; aligned_msg->payload_size = payload_size; memcpy((void *)aligned_msg->payload, payload, payload_size); - put_cpu_ptr(hv_cpu); status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL); + /* Preemption must remain disabled until after the hypercall + * so some other thread can't get scheduled onto this cpu and + * corrupt the per-cpu post_msg_page + */ + put_cpu_ptr(hv_cpu); + return status & 0xFFFF; }