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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-01-10 16:58:00 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-11 09:08:59 -0700
commit78c04996b5888526c7aa3c9debe9dc56519ab81e (patch)
tree388149a91b6029aa120ae1f147712f01bb9efa96 /mm
parentbbe660db23e41647366039c1860cee0891fe9903 (diff)
mm: don't dereference struct page fields of invalid pages
[ 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>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8b80115e4e9e..f9d648fce8cd 100644
--- 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;