Commit e1ee65d8 authored by David Howells's avatar David Howells Committed by Linus Torvalds
Browse files

NOMMU: Fix __get_user_pages() to pin last page on offset buffers 



Fix __get_user_pages() to make it pin the last page on a buffer that doesn't
begin at the start of a page, but is a multiple of PAGE_SIZE in size.

The problem is that __get_user_pages() advances the pointer too much when it
iterates to the next page if the page it's currently looking at isn't used from
the first byte.  This can cause the end of a short VMA to be reached
prematurely, resulting in the last page being lost.

Signed-off-by: default avatarSteven J. Magnani <steve@digidescorp.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7561e8ca

mm/nommu.c

+1 −1
Original line number Diff line number Diff line
@@ -162,7 +162,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 
		}

		if (vmas)

			vmas[i] = vma;

		start += PAGE_SIZE;

		start = (start + PAGE_SIZE) & PAGE_MASK;

	}



	return i;

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