Re: [PATCH v2] vsock/virtio: Fix unsigned integer wrap around in virtio_transport_has_space()

[Stefano Garzarella]

On Mon, Dec 11, 2023 at 07:23:17PM +0300, Nikolay Kuratov wrote:

We need to do signed arithmetic if we expect condition
`if (bytes < 0)` to be possible

Found by Linux Verification Center (linuxtesting.org) with SVACE

Fixes: 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko")
Signed-off-by: Nikolay Kuratov <k...@yandex-team.ru>
---

V1 -> V2: Added Fixes section

Please, next time carry also R-b tags.

net/vmw_vsock/virtio_transport_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefano Garzarella <sgarz...@redhat.com>

Thanks,
Stefano

diff --git a/net/vmw_vsock/virtio_transport_common.c 
b/net/vmw_vsock/virtio_transport_common.c
index c8e162c9d1df..6df246b53260 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -843,7 +843,7 @@ static s64 virtio_transport_has_space(struct vsock_sock 
*vsk)
        struct virtio_vsock_sock *vvs = vsk->trans;
        s64 bytes;

-       bytes = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
+       bytes = (s64)vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
        if (bytes < 0)
                bytes = 0;

--
2.34.1