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authorStefan Hajnoczi <stefanha@redhat.com>2021-05-24 16:40:20 +0100
committerMichael S. Tsirkin <mst@redhat.com>2021-07-03 04:50:53 -0400
commit63947b3434f475418b9677a393d025c0962c2cf8 (patch)
tree96114c339dce8f5912b75e40f65277fccff4cca5 /drivers/block
parent7a43ce37cd595ed7b6e6a48bdb3a598e647aa738 (diff)
virtio-blk: limit seg_max to a safe value
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>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/virtio_blk.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c3e260d5bdd0..4b49df2dfd23 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -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);
@@ -721,7 +724,10 @@ 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) {