Re: [PATCH] um: vector: fix return value check in vector_legacy_rx

[Richard Weinberger <richard@nod.at>]

----- Ursprüngliche Mail -----
> Von: "Johannes Berg" <johannes@sipsolutions.net>
> An: "Richard Weinberger" <richard.weinberger@gmail.com>, "Ma Ke" <make_ruc2021@163.com>
> CC: "richard" <richard@nod.at>, "anton ivanov" <anton.ivanov@cambridgegreys.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 PM 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 = CHECKSUM_UNNECESSARY;
>> >                                 }
>> >                         }
>> > -                       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.
>> 
> We had pretty much the exact same discussion in the other patch ...
> 
> https://patchwork.ozlabs.org/project/linux-um/patch/20231007005104.3994678-1-make_ruc2021@163.com/

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

> 
> 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