Jacob Keller
2023-Feb-27 21:41 UTC
[PATCH] vhost: use struct_size and size_add to compute flex array sizes
The vhost_get_avail_size and vhost_get_used_size functions compute the size of structures with flexible array members with an additional 2 bytes if the VIRTIO_RING_F_EVENT_IDX feature flag is set. Convert these functions to use struct_size() and size_add() instead of coding the calculation by hand. This ensures that the calculations will saturate at SIZE_MAX rather than overflowing. Signed-off-by: Jacob Keller <jacob.e.keller at intel.com> Cc: "Michael S. Tsirkin" <mst at redhat.com> Cc: Jason Wang <jasowang at redhat.com> Cc: virtualization at lists.linux-foundation.org Cc: kvm at vger.kernel.org --- I found this using a coccinelle patch I developed and submitted at [1]. [1]: https://lore.kernel.org/all/20230227202428.3657443-1-jacob.e.keller at intel.com/ drivers/vhost/vhost.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index f11bdbe4c2c5..43fa626d4e44 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -436,8 +436,7 @@ static size_t vhost_get_avail_size(struct vhost_virtqueue *vq, size_t event __maybe_unused vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; - return sizeof(*vq->avail) + - sizeof(*vq->avail->ring) * num + event; + return size_add(struct_size(vq->avail, ring, num), event); } static size_t vhost_get_used_size(struct vhost_virtqueue *vq, @@ -446,8 +445,7 @@ static size_t vhost_get_used_size(struct vhost_virtqueue *vq, size_t event __maybe_unused vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; - return sizeof(*vq->used) + - sizeof(*vq->used->ring) * num + event; + return size_add(struct_size(vq->used, ring, num), event); } static size_t vhost_get_desc_size(struct vhost_virtqueue *vq, -- 2.39.1.405.gd4c25cc71f83
Michael S. Tsirkin
2023-Feb-27 21:53 UTC
[PATCH] vhost: use struct_size and size_add to compute flex array sizes
On Mon, Feb 27, 2023 at 01:41:27PM -0800, Jacob Keller wrote:> The vhost_get_avail_size and vhost_get_used_size functions compute the size > of structures with flexible array members with an additional 2 bytes if the > VIRTIO_RING_F_EVENT_IDX feature flag is set. Convert these functions to use > struct_size() and size_add() instead of coding the calculation by hand. > > This ensures that the calculations will saturate at SIZE_MAX rather than > overflowing. > > Signed-off-by: Jacob Keller <jacob.e.keller at intel.com> > Cc: "Michael S. Tsirkin" <mst at redhat.com> > Cc: Jason Wang <jasowang at redhat.com> > Cc: virtualization at lists.linux-foundation.org > Cc: kvm at vger.kernel.orgAcked-by: Michael S. Tsirkin <mst at redhat.com> Will merge, thanks!> --- > > I found this using a coccinelle patch I developed and submitted at [1]. > > [1]: https://lore.kernel.org/all/20230227202428.3657443-1-jacob.e.keller at intel.com/ > > drivers/vhost/vhost.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index f11bdbe4c2c5..43fa626d4e44 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -436,8 +436,7 @@ static size_t vhost_get_avail_size(struct vhost_virtqueue *vq, > size_t event __maybe_unused > vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; > > - return sizeof(*vq->avail) + > - sizeof(*vq->avail->ring) * num + event; > + return size_add(struct_size(vq->avail, ring, num), event); > } > > static size_t vhost_get_used_size(struct vhost_virtqueue *vq, > @@ -446,8 +445,7 @@ static size_t vhost_get_used_size(struct vhost_virtqueue *vq, > size_t event __maybe_unused > vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX) ? 2 : 0; > > - return sizeof(*vq->used) + > - sizeof(*vq->used->ring) * num + event; > + return size_add(struct_size(vq->used, ring, num), event); > } > > static size_t vhost_get_desc_size(struct vhost_virtqueue *vq, > -- > 2.39.1.405.gd4c25cc71f83