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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id 71sm3162361pfv.8.2020.04.02.00.51.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Apr 2020 00:51:27 -0700 (PDT) Date: Thu, 2 Apr 2020 00:51:26 -0700 From: Kees Cook To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , airlied@linux.ie, daniel@ffwll.ch, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-arch@vger.kernel.org Subject: Re: [PATCH RESEND 2/4] uaccess: Selectively open read or write user access Message-ID: <202004020047.401CEBED2@keescook> References: <27106d62fdbd4ffb47796236050e418131cb837f.1585811416.git.christophe.leroy@c-s.fr> <25040ad2d2a2cef45a2442b0e934141987e11b71.1585811416.git.christophe.leroy@c-s.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <25040ad2d2a2cef45a2442b0e934141987e11b71.1585811416.git.christophe.leroy@c-s.fr> 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 Thu, Apr 02, 2020 at 07:34:17AM +0000, Christophe Leroy wrote: > [...] > diff --git a/kernel/compat.c b/kernel/compat.c > index 843dd17e6078..705ca7e418c6 100644 > --- a/kernel/compat.c > +++ b/kernel/compat.c > @@ -199,7 +199,7 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, > bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); > nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); > > - if (!user_access_begin(umask, bitmap_size / 8)) > + if (!user_write_access_begin(umask, bitmap_size / 8)) This looks mismatched: should be user_read_access_begin()? > return -EFAULT; > > while (nr_compat_longs > 1) { > @@ -211,11 +211,11 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, > } > if (nr_compat_longs) > unsafe_get_user(*mask, umask++, Efault); > - user_access_end(); > + user_read_access_end(); > return 0; > > Efault: > - user_access_end(); > + user_read_access_end(); > return -EFAULT; > } (These correctly end read access.) > > @@ -228,7 +228,7 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, > bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); > nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); > > - if (!user_access_begin(umask, bitmap_size / 8)) > + if (!user_read_access_begin(umask, bitmap_size / 8)) And ..._write_... here? > return -EFAULT; > > while (nr_compat_longs > 1) { > @@ -239,10 +239,10 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, > } > if (nr_compat_longs) > unsafe_put_user((compat_ulong_t)*mask, umask++, Efault); > - user_access_end(); > + user_write_access_end(); > return 0; > Efault: > - user_access_end(); > + user_write_access_end(); > return -EFAULT; > } (These correctly end write access.) All the others look correct. With the above fixed: Reviewed-by: Kees Cook -- Kees Cook