From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by kanga.kvack.org (Postfix) with ESMTP id 3281C6B000C for ; Tue, 2 Oct 2018 09:12:52 -0400 (EDT) Received: by mail-wr1-f69.google.com with SMTP id p12-v6so1622532wrt.19 for ; Tue, 02 Oct 2018 06:12:52 -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 79-v6sor8123862wmf.13.2018.10.02.06.12.50 for (Google Transport Security); Tue, 02 Oct 2018 06:12:50 -0700 (PDT) From: Andrey Konovalov Subject: [PATCH v7 3/8] arm64: untag user addresses in access_ok and __uaccess_mask_ptr Date: Tue, 2 Oct 2018 15:12:38 +0200 Message-Id: <2b957e4f0a3133480dda9d9c8aeceb9b9d9378eb.1538485901.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas , Will Deacon , Mark Rutland , Robin Murphy , Kees Cook , Kate Stewart , Greg Kroah-Hartman , Andrew Morton , Ingo Molnar , "Kirill A . Shutemov" , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@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 , Luc Van Oostenryck , Andrey Konovalov 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(); -- 2.19.0.605.g01d371f741-goog