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([2001:9e8:32e4:1500:aa40:e745:b6c9:7081]) by smtp.gmail.com with ESMTPSA id j4-20020aa7ca44000000b0052574ef0da1sm6830091edt.28.2023.08.30.07.23.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Aug 2023 07:23:11 -0700 (PDT) Message-ID: Subject: Re: [PATCH 1/5] string.h: add array-wrappers for (v)memdup_user() From: pstanner@redhat.com To: Andy Shevchenko Cc: Kees Cook , Andy Shevchenko , Eric Biederman , Christian Brauner , David Disseldorp , Luis Chamberlain , Siddh Raman Pant , Nick Alcock , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Zack Rusin , VMware Graphics Reviewers , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-hardening@vger.kernel.org, David Airlie Date: Wed, 30 Aug 2023 16:23:10 +0200 In-Reply-To: References: <46f667e154393a930a97d2218d8e90286d93a062.1693386602.git.pstanner@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2023-08-30 at 17:15 +0300, Andy Shevchenko wrote: > On Wed, Aug 30, 2023 at 4:46=E2=80=AFPM Philipp Stanner > wrote: >=20 > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (unlikely(check_mul_overflow(n= , size, &nbytes))) > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 return ERR_PTR(-EINVAL); >=20 > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (unlikely(check_mul_overflow(n= , size, &nbytes))) > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 return ERR_PTR(-EINVAL); >=20 > Btw, why not -EOVERFLOW ? >=20 Good question, actually. To be honest I wasn't quite sure which code to pick (-E2BIG was also once I candidate). -EINVAL was picked because the idea was that a request overflowing a size_t could surely be expected to contain an invalid parameter, because no one would ever request an array _that_ large ?