Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Content-Type: text/plain;
        charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\))
Subject: Re: [PATCH] mm/vmalloc: Sanitize __get_vm_area() arguments
From:   William Kucharski <william.kucharski@oracle.com>
In-Reply-To: <20200404185229.GA424@pc636>
Date:   Sat, 4 Apr 2020 23:25:45 -0600
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org, jroedel@suse.de,
        vbabka@suse.cz, Thomas Gleixner <tglx@linutronix.de>
Content-Transfer-Encoding: quoted-printable
Message-Id: <EEB53CBF-0B3F-43E0-94F6-B001918BAC3E@oracle.com>
References: <D25C4027-6EF9-44C2-AD4D-DDC785288B9A@oracle.com>
 <20200404185229.GA424@pc636>
To:     Uladzislau Rezki <urezki@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Apr 4, 2020, at 12:52 PM, Uladzislau Rezki <urezki@gmail.com> =
wrote:
>=20
>>=20
>> =EF=BB=BFIs there any need to similarly sanitize =E2=80=9Csize=E2=80=9D=
 to assure start + size doesn=E2=80=99t go past =E2=80=9Cend?=E2=80=9D
>>=20
> Why is that double check needed if all such tests are done deeper on =
stack?

If such tests ARE performed, then it doesn't matter to me whether it is =
checked before or after,
it just seems that nothing checks whether start + size makes some sort =
of sense with respect
to end.

I admit I didn't walk through all the routines to see if such a check =
would be superfluous.