From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dinh Nguyen Date: Wed, 23 Feb 2022 23:30:53 +0000 Subject: Re: [PATCH v2 07/18] nios2: drop access_ok() check from __put_user() Message-Id: List-Id: References: <20220216131332.1489939-1-arnd@kernel.org> <20220216131332.1489939-8-arnd@kernel.org> In-Reply-To: <20220216131332.1489939-8-arnd@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Arnd Bergmann , Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk Cc: linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, ebiederm@xmission.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org On 2/16/22 07:13, Arnd Bergmann wrote: > From: Arnd Bergmann > > Unlike other architectures, the nios2 version of __put_user() has an > extra check for access_ok(), preventing it from being used to implement > __put_kernel_nofault(). > > Split up put_user() along the same lines as __get_user()/get_user() > > Signed-off-by: Arnd Bergmann > --- > arch/nios2/include/asm/uaccess.h | 56 +++++++++++++++++++------------- > 1 file changed, 33 insertions(+), 23 deletions(-) > > diff --git a/arch/nios2/include/asm/uaccess.h b/arch/nios2/include/asm/uaccess.h > index ca9285a915ef..a5cbe07cf0da 100644 > --- a/arch/nios2/include/asm/uaccess.h > +++ b/arch/nios2/include/asm/uaccess.h > @@ -167,34 +167,44 @@ do { \ > : "r" (val), "r" (ptr), "i" (-EFAULT)); \ > } > > -#define put_user(x, ptr) \ > +#define __put_user_common(__pu_val, __pu_ptr) \ > ({ \ > long __pu_err = -EFAULT; \ > - __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ > - __typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x); \ > - if (access_ok(__pu_ptr, sizeof(*__pu_ptr))) { \ > - switch (sizeof(*__pu_ptr)) { \ > - case 1: \ > - __put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \ > - break; \ > - case 2: \ > - __put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \ > - break; \ > - case 4: \ > - __put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \ > - break; \ > - default: \ > - /* XXX: This looks wrong... */ \ > - __pu_err = 0; \ > - if (copy_to_user(__pu_ptr, &(__pu_val), \ > - sizeof(*__pu_ptr))) \ > - __pu_err = -EFAULT; \ > - break; \ > - } \ > + switch (sizeof(*__pu_ptr)) { \ > + case 1: \ > + __put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \ > + break; \ > + case 2: \ > + __put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \ > + break; \ > + case 4: \ > + __put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \ > + break; \ > + default: \ > + /* XXX: This looks wrong... */ \ > + __pu_err = 0; \ > + if (__copy_to_user(__pu_ptr, &(__pu_val), \ > + sizeof(*__pu_ptr))) \ > + __pu_err = -EFAULT; \ > + break; \ > } \ > __pu_err; \ > }) > > -#define __put_user(x, ptr) put_user(x, ptr) > +#define __put_user(x, ptr) \ > +({ \ > + __auto_type __pu_ptr = (ptr); \ > + typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x); \ > + __put_user_common(__pu_val, __pu_ptr); \ > +}) > + > +#define put_user(x, ptr) \ > +({ \ > + __auto_type __pu_ptr = (ptr); \ > + typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x); \ > + access_ok(__pu_ptr, sizeof(*__pu_ptr)) ? \ > + __put_user_common(__pu_val, __pu_ptr) : \ > + -EFAULT; \ > +}) > > #endif /* _ASM_NIOS2_UACCESS_H */ Acked-by: Dinh Nguyen