netdev - Re: [PATCH v2] net: vmw_vsock: vmci: Check memcpy_from

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Date:   Mon, 5 Dec 2022 10:47:36 +0100
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Artem Chernyshev <artem.chernyshev@...-soft.ru>
Cc:     Vishnu Dasa <vdasa@...are.com>, Bryan Tan <bryantan@...are.com>,
        VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: Re: [PATCH v2] net: vmw_vsock: vmci: Check memcpy_from_msg()

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@...-soft.ru>
>---
>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@...hat.com>

Thanks,
Stefano