Patch "Drivers: hv: balloon: don't crash when memory is added in non-sorted order" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Drivers: hv: balloon: don't crash when memory is added in non-sorted order

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drivers-hv-balloon-don-t-crash-when-memory-is-added-in-non-sorted-order.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 77c0c9735bc0ba5898e637a3a20d6bcb50e3f67d Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Sat, 30 Apr 2016 19:21:35 -0700
Subject: Drivers: hv: balloon: don't crash when memory is added in non-sorted order

From: Vitaly Kuznetsov <vkuznets@redhat.com>

commit 77c0c9735bc0ba5898e637a3a20d6bcb50e3f67d upstream.

When we iterate through all HA regions in handle_pg_range() we have an
assumption that all these regions are sorted in the list and the
'start_pfn >= has->end_pfn' check is enough to find the proper region.
Unfortunately it's not the case with WS2016 where host can hot-add regions
in a different order. We end up modifying the wrong HA region and crashing
later on pages online. Modify the check to make sure we found the region
we were searching for while iterating. Fix the same check in pfn_covered()
as well.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hv/hv_balloon.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -714,7 +714,7 @@ static bool pfn_covered(unsigned long st
 		 * If the pfn range we are dealing with is not in the current
 		 * "hot add block", move on.
 		 */
-		if ((start_pfn >= has->end_pfn))
+		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
 			continue;
 		/*
 		 * If the current hot add-request extends beyond
@@ -768,7 +768,7 @@ static unsigned long handle_pg_range(uns
 		 * If the pfn range we are dealing with is not in the current
 		 * "hot add block", move on.
 		 */
-		if ((start_pfn >= has->end_pfn))
+		if (start_pfn < has->start_pfn || start_pfn >= has->end_pfn)
 			continue;
 
 		old_covered_state = has->covered_end_pfn;


Patches currently in stable-queue which might be from vkuznets@redhat.com are

queue-4.4/drivers-hv-balloon-don-t-crash-when-memory-is-added-in-non-sorted-order.patch
queue-4.4/drivers-hv-avoid-vfree-on-crash.patch
queue-4.4/hv_netvsc-use-skb_get_hash-instead-of-a-homegrown-implementation.patch