media: fix: media: pci: meye: validate offset to avoid arbitrary access

media: fix: media: pci: meye: validate offset to avoid arbitrary access

[ Upstream commit eac7230fdb4672c2cb56f6a01a1744f562c01f80 ]

Motion eye video4linux driver for Sony Vaio PictureBook desn't validate user-controlled parameter
'vma->vm_pgoff', a malicious process might access all of kernel memory from user space by trying
pass different arbitrary address.
Discussion: http://www.openwall.com/lists/oss-security/2018/07/06/1

Signed-off-by: Lao Wei <zrlw@qq.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>