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

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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: <Stable@vger.kernel.org> #4.11
Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Kelley 2017-05-18 10:46:07 -07:00 committed by Greg Kroah-Hartman
parent 3110010896
commit 13b9abfc92
1 changed files with 6 additions and 1 deletions
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7
drivers/hv/hv.c
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@ -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;
}