| From foo@baz Wed Aug 9 11:19:16 PDT 2017 |
| From: Ard Biesheuvel <ard.biesheuvel@linaro.org> |
| Date: Tue, 10 Jan 2017 16:58:00 -0800 |
| Subject: mm: don't dereference struct page fields of invalid pages |
| |
| From: Ard Biesheuvel <ard.biesheuvel@linaro.org> |
| |
| |
| [ Upstream commit f073bdc51771f5a5c7a8d1191bfc3ae371d44de7 ] |
| |
| The VM_BUG_ON() check in move_freepages() checks whether the node id of |
| a page matches the node id of its zone. However, it does this before |
| having checked whether the struct page pointer refers to a valid struct |
| page to begin with. This is guaranteed in most cases, but may not be |
| the case if CONFIG_HOLES_IN_ZONE=y. |
| |
| So reorder the VM_BUG_ON() with the pfn_valid_within() check. |
| |
| Link: http://lkml.kernel.org/r/1481706707-6211-2-git-send-email-ard.biesheuvel@linaro.org |
| Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> |
| Acked-by: Will Deacon <will.deacon@arm.com> |
| Cc: Catalin Marinas <catalin.marinas@arm.com> |
| Cc: Hanjun Guo <hanjun.guo@linaro.org> |
| Cc: Yisheng Xie <xieyisheng1@huawei.com> |
| Cc: Robert Richter <rrichter@cavium.com> |
| Cc: James Morse <james.morse@arm.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <alexander.levin@verizon.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| mm/page_alloc.c | 6 +++--- |
| 1 file changed, 3 insertions(+), 3 deletions(-) |
| |
| --- a/mm/page_alloc.c |
| +++ b/mm/page_alloc.c |
| @@ -1527,14 +1527,14 @@ int move_freepages(struct zone *zone, |
| #endif |
| |
| for (page = start_page; page <= end_page;) { |
| - /* Make sure we are not inadvertently changing nodes */ |
| - VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page); |
| - |
| if (!pfn_valid_within(page_to_pfn(page))) { |
| page++; |
| continue; |
| } |
| |
| + /* Make sure we are not inadvertently changing nodes */ |
| + VM_BUG_ON_PAGE(page_to_nid(page) != zone_to_nid(zone), page); |
| + |
| if (!PageBuddy(page)) { |
| page++; |
| continue; |