From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Subject: Patch "virtio: force vring descriptors to be allocated from lowmem" has been added to the 3.7-stable tree To: will.deacon@arm.com,gregkh@linuxfoundation.org,levinsasha928@gmail.com,rusty@rustcorp.com.au Cc: , From: Date: Tue, 08 Jan 2013 10:27:09 -0800 Message-ID: <13576696291097@kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ASCII Content-Transfer-Encoding: 8bit List-ID: This is a note to let you know that I've just added the patch titled virtio: force vring descriptors to be allocated from lowmem to the 3.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: virtio-force-vring-descriptors-to-be-allocated-from-lowmem.patch and it can be found in the queue-3.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From b92b1b89a33c172c075edccf6afb0edc41d851fd Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 19 Oct 2012 14:03:33 +0100 Subject: virtio: force vring descriptors to be allocated from lowmem From: Will Deacon 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 Cc: Sasha Levin Signed-off-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- drivers/virtio/virtio_ring.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -135,6 +135,13 @@ static int vring_add_indirect(struct vri 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; Patches currently in stable-queue which might be from will.deacon@arm.com are queue-3.7/mm-highmem-export-kmap_to_page-for-modules.patch queue-3.7/arm64-signal-push-the-unwinding-prologue-on-the-signal-stack.patch queue-3.7/virtio-9p-correctly-pass-physical-address-to-userspace-for-high-pages.patch queue-3.7/virtio-force-vring-descriptors-to-be-allocated-from-lowmem.patch