[PATCH 1/3] kvm: ensure non-overlapping intervals in rb_int_insert()

[Michel Lespinasse <walken@google.com>]

The rbtree interval API is designed for handling non-overlapping intervals;
modify rb_int_insert() to guarantee this property is maintained by
returning -EEXIST when attempting to insert a new interval that overlaps
an existing interval.

Also fix an issue where the computation of 'result' could trigger an
integer overflow which would break the rbtree ordering.

Signed-off-by: Michel Lespinasse <walken@google.com>

---
 tools/kvm/util/rbtree-interval.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/kvm/util/rbtree-interval.c b/tools/kvm/util/rbtree-interval.c
index d7fa96a06a92..fd69252bea02 100644
--- a/tools/kvm/util/rbtree-interval.c
+++ b/tools/kvm/util/rbtree-interval.c
@@ -99,13 +99,13 @@ int rb_int_insert(struct rb_root *root, struct rb_int_node *i_node)
 	struct rb_node **node = &root->rb_node, *parent = NULL;
 
 	while (*node) {
-		int result = i_node->low - rb_int(*node)->low;
+		struct rb_int_node *cur = rb_int(*node);
 
 		parent = *node;
-		if (result < 0)
-			node	= &((*node)->rb_left);
-		else if (result > 0)
-			node	= &((*node)->rb_right);
+		if (i_node->high <= cur->low)
+			node = &cur->node.rb_left;
+		else if (cur->high <= i_node->low)
+			node = &cur->node.rb_right;
 		else
 			return -EEXIST;
 	}
-- 
1.7.7.3