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[94.245.46.49]) by smtp.gmail.com with ESMTPSA id k4sm9954742lfo.47.2020.04.05.10.23.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 05 Apr 2020 10:23:29 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Sun, 5 Apr 2020 19:23:15 +0200 To: William Kucharski Cc: Uladzislau Rezki , Peter Zijlstra , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, jroedel@suse.de, vbabka@suse.cz, Thomas Gleixner Subject: Re: [PATCH] mm/vmalloc: Sanitize __get_vm_area() arguments Message-ID: <20200405172315.GA8404@pc636> References: <20200404185229.GA424@pc636> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Apr 04, 2020 at 11:25:45PM -0600, William Kucharski wrote: >=20 >=20 > > On Apr 4, 2020, at 12:52 PM, Uladzislau Rezki wrot= e: > >=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? >=20 > 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. >=20 > I admit I didn't walk through all the routines to see if such a check w= ould be superfluous. >=20 Yes, we check it: static __always_inline bool is_within_this_va(struct vmap_area *va, unsigned long size, unsigned long align, unsigned long vstart) { ... return (nva_start_addr + size <=3D va->va_end); } -- Vlad Rezki