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mm/memory.c: make remap_pfn_range() reject unaligned addr

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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>
This commit is contained in:
Alex Zhang 2020-08-06 23:22:24 -07:00 • committed by Linus Torvalds
parent 463b7a173d
commit 0c4123e3fb
1 changed files with 4 additions and 1 deletions
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5
mm/memory.c
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@ -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 * remap_pfn_range - remap kernel memory to userspace
* @vma: user vma to map to * @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 * @pfn: page frame number of kernel physical memory address
* @size: size of mapping area * @size: size of mapping area
* @prot: page protection flags for this mapping * @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; unsigned long remap_pfn = pfn;
int err; int err;
if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
return -EINVAL;
/* /*
* Physically remapped pages are special. Tell the * Physically remapped pages are special. Tell the
* rest of the world about it: * rest of the world about it: