From: Matthew Wilcox <willy@linux.intel.com>
Date: Sat, 21 May 2016 00:01:59 +0000 (-0700)
Subject: radix-tree: fix sibling entry insertion
X-Git-Tag: v4.7-rc1~89^2~54
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=3b8c00f68405e9c037a6d8ae0d5d9da7f8a34e6a;p=cascardo%2Flinux.git

radix-tree: fix sibling entry insertion

The subtraction was the wrong way round, leading to undefined behaviour
(shift by an amount larger than the size of the type).

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 585965afc808..c0366d1d2613 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -526,8 +526,8 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 
 #ifdef CONFIG_RADIX_TREE_MULTIORDER
 	/* Insert pointers to the canonical entry */
-	if ((shift - order) > 0) {
-		int i, n = 1 << (shift - order);
+	if (order > shift) {
+		int i, n = 1 << (order - shift);
 		offset = offset & ~(n - 1);
 		slot = ptr_to_indirect(&node->slots[offset]);
 		for (i = 0; i < n; i++) {