mm: Force TLB flush for PFNMAP mappings before unlink_file_vma()

stable inclusion
from stable-v5.10.142
commit 895428ee124ad70b9763259308354877b725c31d
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5PE9S
CVE: CVE-2022-39188

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=895428ee124ad70b9763259308354877b725c31d



--------------------------------

commit b67fbebd upstream.

Some drivers rely on having all VMAs through which a PFN might be
accessible listed in the rmap for correctness.
However, on X86, it was possible for a VMA with stale TLB entries
to not be listed in the rmap.

This was fixed in mainline with
commit b67fbebd ("mmu_gather: Force tlb-flush VM_PFNMAP vmas"),
but that commit relies on preceding refactoring in
commit 18ba064e ("mmu_gather: Let there be one tlb_{start,end}_vma()
implementation") and commit 1e9fdf21 ("mmu_gather: Remove per arch
tlb_{start,end}_vma()").

This patch provides equivalent protection without needing that
refactoring, by forcing a TLB flush between removing PTEs in
unmap_vmas() and the call to unlink_file_vma() in free_pgtables().

[This is a stable-specific rewrite of the upstream commit!]
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: ze zuo <zuoze1@huawei.com>
Reviewed-by: Chen Wandun <chenwandun@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>