mm: don't dereference struct page fields of invalid pages
authorArd Biesheuvel <ard.biesheuvel@linaro.org>
Wed, 11 Jan 2017 00:58:00 +0000 (16:58 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 11 Jan 2017 02:31:55 +0000 (18:31 -0800)
commitf073bdc51771f5a5c7a8d1191bfc3ae371d44de7
tree028dad6c091084d148f4b6ea4634ba31235b55bc
parent9ebf73b275f06b114586af27cda3fd72e149d5ba
mm: don't dereference struct page fields of invalid pages

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>
mm/page_alloc.c