linux-kernel - [PATCH] vsock/virtio: Fix unsigned integer wrap around in virtio_transport_has

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Message-Id: <20231211142505.4076725-1-kniv@yandex-team.ru>
Date:   Mon, 11 Dec 2023 17:25:05 +0300
From:   Nikolay Kuratov <kniv@...dex-team.ru>
To:     linux-kernel@...r.kernel.org
Cc:     sgarzare@...hat.com, netdev@...r.kernel.org,
        virtualization@...ts.linux.dev, kvm@...r.kernel.org,
        Nikolay Kuratov <kniv@...dex-team.ru>
Subject: [PATCH] vsock/virtio: Fix unsigned integer wrap around in virtio_transport_has_space()

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

Signed-off-by: Nikolay Kuratov <kniv@...dex-team.ru>
---
 net/vmw_vsock/virtio_transport_common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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