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| author | Will Deacon <will.deacon@arm.com> | 2012-10-19 14:03:33 +0100 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2012-10-22 18:19:49 +1030 |
| commit | b92b1b89a33c172c075edccf6afb0edc41d851fd (patch) | |
| tree | b7ca705150cfa459c4daa7f0c04874839490c291 /drivers/virtio | |
| parent | b9cdc88df8e63e81c723b82c286fc97f5d0dc325 (diff) | |
| download | lwn-b92b1b89a33c172c075edccf6afb0edc41d851fd.tar.gz lwn-b92b1b89a33c172c075edccf6afb0edc41d851fd.zip | |
virtio: force vring descriptors to be allocated from lowmem
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.
Cc: stable@kernel.org
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/virtio')
| -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 e639584b2dbd..286c30cb393d 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -135,6 +135,13 @@ 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; |