2023-12-11 14:28:22

by Nikolay Kuratov

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 <[email protected]>
---
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

2023-12-11 15:47:34

by Stefano Garzarella

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

On Mon, Dec 11, 2023 at 05:25:05PM +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
>

We should add:

Fixes: 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko")

>Signed-off-by: Nikolay Kuratov <[email protected]>
>---
> 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 we respect the credit, this should not happen. It can happen, though,
that the receiver changes its buffer size while we're communicating,
and if it reduces it, this could happen. So yes, we need to fix it!

Thanks!

Reviewed-by: Stefano Garzarella <[email protected]>

> if (bytes < 0)
> bytes = 0;
>
>--
>2.34.1
>

2023-12-11 16:24:07

by Nikolay Kuratov

Subject: [PATCH v2] 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

Fixes: 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko")
Signed-off-by: Nikolay Kuratov <[email protected]>
---

V1 -> V2: Added Fixes section

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

2023-12-11 16:34:03

by Stefano Garzarella

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

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 <[email protected]>
>---
>
>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 <[email protected]>

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
>
>

2023-12-14 02:31:22

by patchwork-bot+netdevbpf

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

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <[email protected]>:

On Mon, 11 Dec 2023 19:23:17 +0300 you 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 <[email protected]>
>
> [...]

Here is the summary with links:
- [v2] vsock/virtio: Fix unsigned integer wrap around in virtio_transport_has_space()
https://git.kernel.org/netdev/net/c/60316d7f10b1

You are awesome, thank you!
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