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From:   Akihiro Suda <suda.kyoto@gmail.com>
Date:   Fri, 2 Jun 2023 22:03:41 +0900
Message-ID: <CAG8fp8R+2TztxYKcLwU354mQ47mD7RPQKarxnzA+j2ydtqamBg@mail.gmail.com>
Subject: Re: [PATCH linux] net/ipv4: ping_group_range: allow GID from
 2147483648 to 4294967294
To:     David Laight <David.Laight@aculab.com>
Cc:     Kuniyuki Iwashima <kuniyu@amazon.com>,
        "edumazet@google.com" <edumazet@google.com>,
        "akihiro.suda.cz@hco.ntt.co.jp" <akihiro.suda.cz@hco.ntt.co.jp>,
        "akihirosuda@git.sr.ht" <akihirosuda@git.sr.ht>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "pabeni@redhat.com" <pabeni@redhat.com>,
        "segoon@openwall.com" <segoon@openwall.com>
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2023=E5=B9=B46=E6=9C=882=E6=97=A5(=E9=87=91) 19:51 David Laight <David.Laig=
ht@aculab.com>:
>
> From: Kuniyuki Iwashima
> > Sent: 01 June 2023 00:00
> ....
> > > > --- a/include/net/ping.h
> > > > +++ b/include/net/ping.h
> > > > @@ -20,7 +20,7 @@
> > > >   * gid_t is either uint or ushort.  We want to pass it to
> > > >   * proc_dointvec_minmax(), so it must not be larger than MAX_INT
> > > >   */
> > > > -#define GID_T_MAX (((gid_t)~0U) >> 1)
> > > > +#define GID_T_MAX ((gid_t)~0U)
>
> Doesn't that comment need updating?
>
> I do wonder how much code breaks for gid > MAXINT.
> How much testing does it actually get??

It is fixed in v3:
https://patchwork.kernel.org/project/netdevbpf/patch/20230601031305.55901-1=
-akihiro.suda.cz@hco.ntt.co.jp/

```
-/*
- * gid_t is either uint or ushort.  We want to pass it to
- * proc_dointvec_minmax(), so it must not be larger than MAX_INT
- */
-#define GID_T_MAX (((gid_t)~0U) >> 1)
+#define GID_T_MAX (((gid_t)~0U) - 1)
```

Tested with 4294967294, 4294967295 (EINVAL), and 4294967296 (EINVAL), on x8=
6_64.


>         David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1=
 1PT, UK
> Registration No: 1397386 (Wales)