Received-SPF: pass (google.com: domain of linux-kernel+bounces-17222-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Precedence: bulk
MIME-Version: 1.0
References: <20231006122717.3984017-1-make_ruc2021@163.com>
In-Reply-To: <20231006122717.3984017-1-make_ruc2021@163.com>
From: Richard Weinberger <richard.weinberger@gmail.com>
Date: Thu, 4 Jan 2024 22:05:50 +0100
Message-ID: <CAFLxGvytpwjXM0bdLrxt0itfEBPqJSmuM6otB7dTBmsTaAAPgw@mail.gmail.com>
Subject: Re: [PATCH] um: vector: fix return value check in vector_legacy_rx
To: Ma Ke <make_ruc2021@163.com>
Cc: richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, 
	xiangyang3@huawei.com, linux-um@lists.infradead.org, 
	linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Fri, Oct 6, 2023 at 2:28=E2=80=AFPM Ma Ke <make_ruc2021@163.com> wrote:
>
> In vector_legacy_rx, to avoid an unexpected result returned by
> pskb_trim, we should check the return value of pskb_trim().
>
> Signed-off-by: Ma Ke <make_ruc2021@163.com>
> ---
>  arch/um/drivers/vector_kern.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.=
c
> index 131b7cb29576..822a8c0cdcc1 100644
> --- a/arch/um/drivers/vector_kern.c
> +++ b/arch/um/drivers/vector_kern.c
> @@ -890,7 +890,8 @@ static int vector_legacy_rx(struct vector_private *vp=
)
>                                         skb->ip_summed =3D CHECKSUM_UNNEC=
ESSARY;
>                                 }
>                         }
> -                       pskb_trim(skb, pkt_len - vp->rx_header_size);
> +                       if (pskb_trim(skb, pkt_len - vp->rx_header_size))
> +                               return 0;

I think this adds a memory leak. Also, can pskb_trim() really fail in
this scenario?
The function controls skb creation and knows all lengths.