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| author | Andrea Arcangeli <aarcange@redhat.com> | 2018-11-30 14:09:32 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-08 13:03:38 +0100 |
| commit | 705a2810a314ccf06fe6190ea555e586975f9b28 (patch) | |
| tree | 69bceadfa3f17297ec9cbe1ec874deb07a81fe4e /mm | |
| parent | 6ea54af90988bf869e57265723c33af623b4abec (diff) | |
| download | linux-exynos-705a2810a314ccf06fe6190ea555e586975f9b28.tar.gz linux-exynos-705a2810a314ccf06fe6190ea555e586975f9b28.tar.bz2 linux-exynos-705a2810a314ccf06fe6190ea555e586975f9b28.zip | |
userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas
commit 29ec90660d68bbdd69507c1c8b4e33aa299278b1 upstream.
After the VMA to register the uffd onto is found, check that it has
VM_MAYWRITE set before allowing registration. This way we inherit all
common code checks before allowing to fill file holes in shmem and
hugetlbfs with UFFDIO_COPY.
The userfaultfd memory model is not applicable for readonly files unless
it's a MAP_PRIVATE.
Link: http://lkml.kernel.org/r/20181126173452.26955-4-aarcange@redhat.com
Fixes: ff62a3421044 ("hugetlb: implement memfd sealing")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Hugh Dickins <hughd@google.com>
Reported-by: Jann Horn <jannh@google.com>
Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Cc: <stable@vger.kernel.org>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/userfaultfd.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 8da1cd8cea89..5d70fdbd8bc0 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -228,8 +228,9 @@ retry: if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) goto out_unlock; /* - * Only allow __mcopy_atomic_hugetlb on userfaultfd - * registered ranges. + * Check the vma is registered in uffd, this is + * required to enforce the VM_MAYWRITE check done at + * uffd registration time. */ if (!dst_vma->vm_userfaultfd_ctx.ctx) goto out_unlock; @@ -472,13 +473,9 @@ retry: if (!dst_vma) goto out_unlock; /* - * Be strict and only allow __mcopy_atomic on userfaultfd - * registered ranges to prevent userland errors going - * unnoticed. As far as the VM consistency is concerned, it - * would be perfectly safe to remove this check, but there's - * no useful usage for __mcopy_atomic ouside of userfaultfd - * registered ranges. This is after all why these are ioctls - * belonging to the userfaultfd and not syscalls. + * Check the vma is registered in uffd, this is required to + * enforce the VM_MAYWRITE check done at uffd registration + * time. */ if (!dst_vma->vm_userfaultfd_ctx.ctx) goto out_unlock; |