From 0c4123e3fb82d6014d0a70b52eb38153f658541c Mon Sep 17 00:00:00 2001 From: Alex Zhang <zhangalex@google.com> Date: Thu, 6 Aug 2020 23:22:24 -0700 Subject: [PATCH] mm/memory.c: make remap_pfn_range() reject unaligned addr This function implicitly assumes that the addr passed in is page aligned. A non page aligned addr could ultimately cause a kernel bug in remap_pte_range as the exit condition in the logic loop may never be satisfied. This patch documents the need for the requirement, as well as explicitly adds a check for it. Signed-off-by: Alex Zhang <zhangalex@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200617233512.177519-1-zhangalex@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index f4f27b9d48c5b..c39a13b09602c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2082,7 +2082,7 @@ static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, /** * remap_pfn_range - remap kernel memory to userspace * @vma: user vma to map to - * @addr: target user address to start at + * @addr: target page aligned user address to start at * @pfn: page frame number of kernel physical memory address * @size: size of mapping area * @prot: page protection flags for this mapping @@ -2101,6 +2101,9 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, unsigned long remap_pfn = pfn; int err; + if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) + return -EINVAL; + /* * Physically remapped pages are special. Tell the * rest of the world about it: -- GitLab