From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Fri, 20 Nov 2015 15:35:23 +0000 Subject: [PATCH 1/2] arm64: mm: detect bad __create_mapping uses Message-ID: <1448033724-13846-1-git-send-email-mark.rutland@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org If a caller of __create_mapping provides a PA and VA which have different sub-page offsets, it is not clear which offset they expect to apply to the mapping, and is indicative of a bad caller. Disallow calls with differing sub-page offsets, and WARN when they are encountered, so that we can detect and fix such cases. Signed-off-by: Mark Rutland Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: Laura Abbott Cc: Steve Capper Cc: Will Deacon --- arch/arm64/mm/mmu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index e3f563c..3b06afa 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -300,6 +300,13 @@ static void __create_mapping(struct mm_struct *mm, pgd_t *pgd, { unsigned long addr, length, end, next; + /* + * If the virtual and physical address don't have the same offset + * within a page, we cannot map the region as the caller expects. + */ + if (WARN_ON((phys ^ virt) & ~PAGE_MASK)) + return; + addr = virt & PAGE_MASK; length = PAGE_ALIGN(size + (virt & ~PAGE_MASK)); -- 1.9.1