diff options
| author | Will Deacon <will.deacon@arm.com> | 2012-10-19 14:03:33 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-11 09:06:47 -0800 |
| commit | 6cb6a94380506d9e5491b8e145811bd676ce6f3d (patch) | |
| tree | 4f1dfd2b85e55b09f971439ca8bee7bbde63cd32 | |
| parent | 4511ba021ea5ee7f2b76d954fc23c3814ac07cba (diff) | |
virtio: force vring descriptors to be allocated from lowmem
commit b92b1b89a33c172c075edccf6afb0edc41d851fd upstream.
Virtio devices may attempt to add descriptors to a virtqueue from atomic
context using GFP_ATOMIC allocation. This is problematic because such
allocations can fall outside of the lowmem mapping, causing virt_to_phys
to report bogus physical addresses which are subsequently passed to
userspace via the buffers for the virtual device.
This patch masks out __GFP_HIGH and __GFP_HIGHMEM from the requested
flags when allocating descriptors for a virtqueue. If an atomic
allocation is requested and later fails, we will return -ENOSPC which
will be handled by the driver.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 5aa43c3392a..52bfd0786fc 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -132,6 +132,13 @@ static int vring_add_indirect(struct vring_virtqueue *vq, unsigned head; int i; + /* + * We require lowmem mappings for the descriptors because + * otherwise virt_to_phys will give us bogus addresses in the + * virtqueue. + */ + gfp &= ~(__GFP_HIGHMEM | __GFP_HIGH); + desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); if (!desc) return -ENOMEM; |