On Fri, Sep 3, 2021 at 8:11 PM Philippe Mathieu-Daudé wrote:
>
> Per
> https://discourse.gnome.org/t/port-your-module-from-g-memdup-to-g-memdup2-now/5538
>
> The old API took the size of the memory to duplicate as a guint,
> whereas most memory functions take memory sizes as a gsize. This
> made it easy to accidentally pass a gsize to g_memdup(). For large
> values, that would lead to a silent truncation of the size from 64
> to 32 bits, and result in a heap area being returned which is
> significantly smaller than what the caller expects. This can likely
> be exploited in various modules to cause a heap buffer overflow.
>
> Replace g_memdup() by the safer g_memdup2() wrapper.
>
> Signed-off-by: Philippe Mathieu-Daudé
> ---
> Should we check in_num/out_num in range?
I'd say it is not needed to check: virtqueue_pop fills them by
iterating through the descriptor chain so the range is restricted to
[0, 1024].
Acked-by: Eugenio Pérez
> ---
> hw/net/virtio-net.c | 3 ++-
> hw/virtio/virtio-crypto.c | 6 +++---
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 16d20cdee52..338fbeb8c57 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1449,7 +1449,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev,
> VirtQueue *vq)
> }
>
> iov_cnt = elem->out_num;
> -iov2 = iov = g_memdup(elem->out_sg, sizeof(struct iovec) *
> elem->out_num);
> +iov2 = iov = g_memdup2(elem->out_sg,
> + sizeof(struct iovec) * elem->out_num);
> s = iov_to_buf(iov, iov_cnt, 0, , sizeof(ctrl));
> iov_discard_front(, _cnt, sizeof(ctrl));
> if (s != sizeof(ctrl)) {
> diff --git a/hw/virtio/virtio-crypto.c b/hw/virtio/virtio-crypto.c
> index 54f9bbb789c..59886c1790d 100644
> --- a/hw/virtio/virtio-crypto.c
> +++ b/hw/virtio/virtio-crypto.c
> @@ -242,7 +242,7 @@ static void virtio_crypto_handle_ctrl(VirtIODevice *vdev,
> VirtQueue *vq)
> }
>
> out_num = elem->out_num;
> -out_iov_copy = g_memdup(elem->out_sg, sizeof(out_iov[0]) * out_num);
> +out_iov_copy = g_memdup2(elem->out_sg, sizeof(out_iov[0]) * out_num);
> out_iov = out_iov_copy;
>
> in_num = elem->in_num;
> @@ -605,11 +605,11 @@ virtio_crypto_handle_request(VirtIOCryptoReq *request)
> }
>
> out_num = elem->out_num;
> -out_iov_copy = g_memdup(elem->out_sg, sizeof(out_iov[0]) * out_num);
> +out_iov_copy = g_memdup2(elem->out_sg, sizeof(out_iov[0]) * out_num);
> out_iov = out_iov_copy;
>
> in_num = elem->in_num;
> -in_iov_copy = g_memdup(elem->in_sg, sizeof(in_iov[0]) * in_num);
> +in_iov_copy = g_memdup2(elem->in_sg, sizeof(in_iov[0]) * in_num);
> in_iov = in_iov_copy;
>
> if (unlikely(iov_to_buf(out_iov, out_num, 0, , sizeof(req))
> --
> 2.31.1
>
>
