Commit 0c4123e3 authored Aug 06, 2020 by Alex Zhang Committed by Linus Torvalds Aug 07, 2020

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>

parent 463b7a17

mm/memory.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -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:

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