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UPSTREAM: virtio-blk: limit seg_max to a safe value

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The struct virtio_blk_config seg_max value is read from the device and
incremented by 2 to account for the request header and status byte
descriptors added by the driver.

In preparation for supporting untrusted virtio-blk devices, protect
against integer overflow and limit the value to a safe maximum.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Link: https://lore.kernel.org/r/20210524154020.98195-1-stefanha@redhat.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 63947b3434)
Bug: 196772804
Signed-off-by: Keir Fraser <keirf@google.com>
Change-Id: Ia239cc17c912f05ed2bad08c5ae8a9b1326d3ae6
This commit is contained in:
Stefan Hajnoczi
2021-05-24 16:40:20 +01:00
committed by Keir Fraser
parent 255b30f804
commit 30d7caeb15
1 changed files with 7 additions and 1 deletions
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8
drivers/block/virtio_blk.c
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@@ -21,6 +21,9 @@
#define VQ_NAME_LEN 16
#define MAX_DISCARD_SEGMENTS 256u
/* The maximum number of sg elements that fit into a virtqueue */
#define VIRTIO_BLK_MAX_SG_ELEMS 32768
static int major;
static DEFINE_IDA(vd_index_ida);
@@ -730,7 +733,10 @@ static int virtblk_probe(struct virtio_device *vdev)
if (err || !sg_elems)
sg_elems = 1;
/* We need an extra sg elements at head and tail. */
/* Prevent integer overflows and honor max vq size */
sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);
/* We need extra sg elements at head and tail. */
sg_elems += 2;
vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
if (!vblk) {