Re: [PATCH v2] net: vmw_vsock: vmci: Check memcpy_from_msg()

[Stefano Garzarella]

On Sat, Dec 03, 2022 at 11:33:12AM +0300, Artem Chernyshev wrote:
> vmci_transport_dgram_enqueue() does not check the return value
> of memcpy_from_msg(). Return with an error if the memcpy fails.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 0f7db23a07af ("vmci_transport: switch ->enqeue_dgram, ->enqueue_stream and ->dequeue_stream to msghdr")
> Signed-off-by: Artem Chernyshev <artem.chernyshev@xxxxxxxxxxx>
> ---
> V1->V2 Fix memory leaking and updates for description
>
> net/vmw_vsock/vmci_transport.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
> index 842c94286d31..c94c3deaa09d 100644
> --- a/net/vmw_vsock/vmci_transport.c
> +++ b/net/vmw_vsock/vmci_transport.c
> @@ -1711,7 +1711,10 @@ static int vmci_transport_dgram_enqueue(
> 	if (!dg)
> 		return -ENOMEM;
>
> -	memcpy_from_msg(VMCI_DG_PAYLOAD(dg), msg, len);
> +	if (memcpy_from_msg(VMCI_DG_PAYLOAD(dg), msg, len)) {
> +		kfree(dg);
> +		return -EFAULT;

Since memcpy_from_msg() is a wrapper of copy_from_iter_full() that 
simply returns -EFAULT in case of an error, perhaps it would be better 
here to return the value of memcpy_from_msg() instead of wiring the 
error.

However in the end the behavior is the same, so even if you don't want 
to change it I'll leave my R-b:

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>

Thanks,
Stefano