From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Konovalov Subject: [PATCH 3/6] arm64: untag user addresses in copy_from_user and others Date: Wed, 18 Apr 2018 20:53:12 +0200 Message-ID: <949c343a4b02b41b80f324c2b7cd56b75e6a04f3.1524077494.git.andreyknvl__39696.6648906984$1524077624$gmane$org@google.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: In-Reply-To: References: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Catalin Marinas , Will Deacon , Jonathan Corbet , Mark Rutland , Robin Murphy , Al Viro , Andrey Konovalov , James Morse , Kees Cook , Bart Van Assche , Kate Stewart , Greg Kroah-Hartman , Thomas Gleixner , Philippe Ombredanne , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Dan Williams , "Aneesh Kumar K . V" , Zi Yan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.orglin Cc: Jacob Bramley , Ruben Ayrapetyan , Lee Smith , Kostya Serebryany , Dmitry Vyukov , Ramana Radhakrishnan , Evgeniy Stepanov List-Id: linux-mm.kvack.org copy_from_user (and a few other similar functions) are used to copy data from user memory into the kernel memory or vice versa. Since a user can provided a tagged pointer to one of the syscalls that use copy_from_user, we need to correctly handle such pointers. Do this by untagging user pointers in access_ok and in __uaccess_mask_ptr. Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/uaccess.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 2d6451cbaa86..24a221678fe3 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -105,7 +105,8 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si #define untagged_addr(addr) \ ((__typeof__(addr))sign_extend64((__u64)(addr), 55)) -#define access_ok(type, addr, size) __range_ok(addr, size) +#define access_ok(type, addr, size) \ + __range_ok(untagged_addr(addr), size) #define user_addr_max get_fs #define _ASM_EXTABLE(from, to) \ @@ -238,12 +239,15 @@ static inline void uaccess_enable_not_uao(void) /* * Sanitise a uaccess pointer such that it becomes NULL if above the * current addr_limit. + * Also untag user pointers that have the top byte tag set. */ #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr) static inline void __user *__uaccess_mask_ptr(const void __user *ptr) { void __user *safe_ptr; + ptr = untagged_addr(ptr); + asm volatile( " bics xzr, %1, %2\n" " csel %0, %1, xzr, eq\n" -- 2.17.0.484.g0c8726318c-goog