Commit ec39c02d authored by Michael Kelley's avatar Michael Kelley Committed by Greg Kroah-Hartman

Drivers: hv: vmbus: Close timing hole that can corrupt per-cpu page

commit 13b9abfc upstream.

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.
Signed-off-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9b5eaef1
......@@ -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;
}
......
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