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Date: Fri, 5 Jan 2024 09:52:45 +0100 (CET)
From: Richard Weinberger <richard@nod.at>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Ma Ke <make_ruc2021@163.com>, anton ivanov <anton.ivanov@cambridgegreys.com>, 
	xiangyang3@huawei.com, linux-um <linux-um@lists.infradead.org>, 
	linux-kernel <linux-kernel@vger.kernel.org>
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References: <20231006122717.3984017-1-make_ruc2021@163.com> <CAFLxGvytpwjXM0bdLrxt0itfEBPqJSmuM6otB7dTBmsTaAAPgw@mail.gmail.com> <1c098c26132b60ebebc46a39e8b7827a29e3a166.camel@sipsolutions.net>
Subject: Re: [PATCH] um: vector: fix return value check in vector_legacy_rx
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Thread-Topic: vector: fix return value check in vector_legacy_rx
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----- Urspr=C3=BCngliche Mail -----
> Von: "Johannes Berg" <johannes@sipsolutions.net>
> An: "Richard Weinberger" <richard.weinberger@gmail.com>, "Ma Ke" <make_ru=
c2021@163.com>
> CC: "richard" <richard@nod.at>, "anton ivanov" <anton.ivanov@cambridgegre=
ys.com>, xiangyang3@huawei.com, "linux-um"
> <linux-um@lists.infradead.org>, "linux-kernel" <linux-kernel@vger.kernel.=
org>
> Gesendet: Freitag, 5. Januar 2024 09:42:12
> Betreff: Re: [PATCH] um: vector: fix return value check in vector_legacy_=
rx

> On Thu, 2024-01-04 at 22:05 +0100, Richard Weinberger wrote:
>> On Fri, Oct 6, 2023 at 2:28=E2=80=AFPM Ma Ke <make_ruc2021@163.com> wrot=
e:
>> >=20
>> > In vector_legacy_rx, to avoid an unexpected result returned by
>> > pskb_trim, we should check the return value of pskb_trim().
>> >=20
>> > Signed-off-by: Ma Ke <make_ruc2021@163.com>
>> > ---
>> >  arch/um/drivers/vector_kern.c | 3 ++-
>> >  1 file changed, 2 insertions(+), 1 deletion(-)
>> >=20
>> > diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_ke=
rn.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_UN=
NECESSARY;
>> >                                 }
>> >                         }
>> > -                       pskb_trim(skb, pkt_len - vp->rx_header_size);
>> > +                       if (pskb_trim(skb, pkt_len - vp->rx_header_siz=
e))
>> > +                               return 0;
>>=20
>> 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.
>>=20
> We had pretty much the exact same discussion in the other patch ...
>=20
> https://patchwork.ozlabs.org/project/linux-um/patch/20231007005104.399467=
8-1-make_ruc2021@163.com/

Yeah, I saw that discussion after commenting to this patch.
(My fault, I scanned patchwork bottom up)=20

>=20
> No point arguing with people who care about static checkers only, I
> guess. This person here never even came back to respond to the comments,
> my take is they're throwing patches over the wall they didn't think
> about, just to see what sticks.

Drive-by fixes are often a waste of everyone's time. :-(

Thanks,
//richard