Commit 6da2d377 authored Feb 24, 2009 by Ian Abbott Committed by Greg Kroah-Hartman Mar 24, 2009

UIO: Take offset into account when determining number of pages that can be mapped



If a UIO memory region does not start on a page boundary but straddles one,
the number of actual pages that overlap the memory region may be calculated
incorrectly because the offset isn't taken into account.  If userspace sets
the mmap length to offset+size, it may fail with -EINVAL if UIO thinks it's
trying to allocate too many pages.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 1bafeb37

drivers/uio/uio.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -708,7 +708,8 @@ static int uio_mmap(struct file filep, struct vm_area_struct vma)
		return -EINVAL;

		requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
		actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
		actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
		+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
		if (requested_pages > actual_pages)
		return -EINVAL;

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