[095/163] mm/memory.c: make remap_pfn_range() reject unaligned addr
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Message ID 20200807062224.b7xjNHWMw%akpm@linux-foundation.org
State New
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Series
  • [001/163] mm/memory.c: avoid access flag update TLB flush for retried page fault
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Commit Message

Andrew Morton Aug. 7, 2020, 6:22 a.m. UTC
From: Alex Zhang <zhangalex@google.com>
Subject: 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.

Link: http://lkml.kernel.org/r/20200617233512.177519-1-zhangalex@google.com
Signed-off-by: Alex Zhang <zhangalex@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Patch
diff mbox series

--- a/mm/memory.c~mm-memoryc-make-remap_pfn_range-reject-unaligned-addr
+++ a/mm/memory.c
@@ -2082,7 +2082,7 @@  static inline int remap_p4d_range(struct
 /**
  * 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_struc
 	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: