From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id E82126B000E for ; Fri, 25 May 2018 13:21:25 -0400 (EDT) Received: by mail-wr0-f199.google.com with SMTP id j8-v6so4259441wrh.18 for ; Fri, 25 May 2018 10:21:25 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id d7-v6sor4941170wrq.34.2018.05.25.10.21.24 for (Google Transport Security); Fri, 25 May 2018 10:21:24 -0700 (PDT) From: Andrey Konovalov Subject: [PATCH v3 3/6] arm64: untag user addresses in access_ok and __uaccess_mask_ptr Date: Fri, 25 May 2018 19:21:13 +0200 Message-Id: <13e2b2fc8d95fda2441d3ed818451e5b5570bcde.1527268727.git.andreyknvl@google.com> In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Al Viro , Andrey Konovalov , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Chintan Pandya 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, before performing access validity checks. Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/uaccess.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 2d6451cbaa86..fa7318d3d7d5 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) \ @@ -237,7 +238,8 @@ static inline void uaccess_enable_not_uao(void) /* * Sanitise a uaccess pointer such that it becomes NULL if above the - * current addr_limit. + * current addr_limit. In case the pointer is tagged (has the top byte set), + * untag the pointer before checking. */ #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr) static inline void __user *__uaccess_mask_ptr(const void __user *ptr) @@ -245,10 +247,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) void __user *safe_ptr; asm volatile( - " bics xzr, %1, %2\n" + " bics xzr, %3, %2\n" " csel %0, %1, xzr, eq\n" : "=&r" (safe_ptr) - : "r" (ptr), "r" (current_thread_info()->addr_limit) + : "r" (ptr), "r" (current_thread_info()->addr_limit), + "r" (untagged_addr(ptr)) : "cc"); csdb(); -- 2.17.0.921.gf22659ad46-goog