]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
userfaultfd: shmem: add i_size checks
authorAndrea Arcangeli <aarcange@redhat.com>
Fri, 30 Nov 2018 22:09:37 +0000 (14:09 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 30 Nov 2018 22:56:14 +0000 (14:56 -0800)
commite2a50c1f64145a04959df2442305d57307e5395a
tree5b4f22c5fdb7faea628f8a3a0c5f9df5454decf4
parent29ec90660d68bbdd69507c1c8b4e33aa299278b1
userfaultfd: shmem: add i_size checks

With MAP_SHARED: recheck the i_size after taking the PT lock, to
serialize against truncate with the PT lock.  Delete the page from the
pagecache if the i_size_read check fails.

With MAP_PRIVATE: check the i_size after the PT lock before mapping
anonymous memory or zeropages into the MAP_PRIVATE shmem mapping.

A mostly irrelevant cleanup: like we do the delete_from_page_cache()
pagecache removal after dropping the PT lock, the PT lock is a spinlock
so drop it before the sleepable page lock.

Link: http://lkml.kernel.org/r/20181126173452.26955-5-aarcange@redhat.com
Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
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>
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>
mm/shmem.c
mm/userfaultfd.c