From b87c48d774bd12f6cb08ad8e5d2671d72bcfd4b4 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 22 Sep 2011 15:48:58 +0800 Subject: Resource: fix wrong resource window calculation commit 47ea91b4052d9e94b9dca5d7a3d947fbebd07ba9 upstream. __find_resource() incorrectly returns a resource window which overlaps an existing allocated window. This happens when the parent's resource-window spans 0x00000000 to 0xffffffff and is entirely allocated to all its children resource-windows. __find_resource() looks for gaps in resource allocation among the children resource windows. When it encounters the last child window it blindly tries the range next to one allocated to the last child. Since the last child's window ends at 0xffffffff the calculation overflows, leading the algorithm to believe that any window in the range 0x0000000 to 0xfffffff is available for allocation. This leads to a conflicting window allocation. Michal Ludvig reported this issue seen on his platform. The following patch fixes the problem and has been verified by Michal. I believe this bug has been there for ages. It got exposed by git commit 2bbc6942273b ("PCI : ability to relocate assigned pci-resources") Signed-off-by: Ram Pai Tested-by: Michal Ludvig Signed-off-by: Linus Torvalds Cc: Herton Ronaldo Krzesinski Signed-off-by: Greg Kroah-Hartman --- kernel/resource.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/resource.c b/kernel/resource.c index 3ff40178dce7..b29b83d042f6 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -419,6 +419,9 @@ static int __find_resource(struct resource *root, struct resource *old, else tmp.end = root->end; + if (tmp.end < tmp.start) + goto next; + resource_clip(&tmp, constraint->min, constraint->max); arch_remove_reservations(&tmp); @@ -436,8 +439,10 @@ static int __find_resource(struct resource *root, struct resource *old, return 0; } } - if (!this) + +next: if (!this || this->end == root->end) break; + if (this != old) tmp.start = this->end + 1; this = this->sibling; -- cgit v1.2.3