From: Alex Zhang zhangalex@google.com
commit 0c4123e3fb82d6014d0a70b52eb38153f658541c upstream
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 (cherry picked from commit 0c4123e3fb82d6014d0a70b52eb38153f658541c) Signed-off-by: Harshvardhan Jha harshvardhan.j.jha@oracle.com --- mm/memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c index 50503743724cc..1d009d3d87b34 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1920,7 +1920,7 @@ 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 @@ -1939,6 +1939,9 @@ 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: