On Wed, Aug 31, 2022 at 09:13:48PM +0200, Jann Horn wrote:
commit b67fbebd4cf980aecbcc750e1462128bffe8ae15 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 b67fbebd4cf9 ("mmu_gather: Force tlb-flush VM_PFNMAP vmas"), but that commit relies on preceding refactoring in commit 18ba064e42df3 ("mmu_gather: Let there be one tlb_{start,end}_vma() implementation") and commit 1e9fdf21a4339 ("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
Now queued up, thanks.
greg k-h