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[209.85.220.65]) by mx.google.com with SMTPS id f7sor1108276wrv.24.2019.02.22.04.53.34 for (Google Transport Security); Fri, 22 Feb 2019 04:53:34 -0800 (PST) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=IZO5qs1i; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=LYedl6oW+X0hODfB6yBlRZE+wsBGKemR/gV1w08gXes=; b=IZO5qs1iTdFS0J8b6mUPkT96MHj4TvOOl4p+NkYj+K5QoPzgtV+ykf7Zu+OkLcqN2H XG3Gh3bG0jBem6M7NTIzz/wK5zl+vCUUNfkfJALSmU8Wj9A1u4sBy3ay4BW4/EmB0HRO rjkA4MwD6TdBTXlf++HuBJnMCfJk5iZzI3+4sXCvRuZvNLxSnSX00w7f+r2eMb9tbUeZ wKQkxlkxUte2ekBF+Cqk930FiD2BqGhYurasbJZ5Cy6szPm8dYUDDnFl+i7USfSEW4tE b+242VIYnFJCUhKNVLIKvM7y8Jwt7Fku92E8DCxmA2ENAr03DmnPf5Nks+jfBd0lKf0N y0ng== X-Google-Smtp-Source: AHgI3Ibs8M2cAwjQZj6orbXxkxYi8LGidQwEOKdpOteZ9oefSzL6DNYvYhuV2aOjewxHuzIPLDjC/Q== X-Received: by 2002:adf:e90b:: with SMTP id f11mr2972186wrm.36.1550840013762; Fri, 22 Feb 2019 04:53:33 -0800 (PST) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:13:8ce:d7fa:9f4c:492]) by smtp.gmail.com with ESMTPSA id o14sm808209wrp.34.2019.02.22.04.53.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Feb 2019 04:53:32 -0800 (PST) From: Andrey Konovalov 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 , Vincenzo Frascino , 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 , Dave Martin , Kevin Brodsky , Szabolcs Nagy , Andrey Konovalov Subject: [PATCH v10 02/12] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Date: Fri, 22 Feb 2019 13:53:14 +0100 Message-Id: X-Mailer: git-send-email 2.21.0.rc0.258.g878e2cd30e-goog In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: 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. Note, that this patch only temporarily untags the pointers to perform the checks, but then passes them as is into the kernel internals. Reviewed-by: Catalin Marinas Signed-off-by: Andrey Konovalov --- arch/arm64/include/asm/uaccess.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 547d7a0c9d05..9b9291abda88 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -95,7 +95,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si return ret; } -#define access_ok(addr, size) __range_ok(addr, size) +#define access_ok(addr, size) __range_ok(untagged_addr(addr), size) #define user_addr_max get_fs #define _ASM_EXTABLE(from, to) \ @@ -227,7 +227,8 @@ 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) @@ -235,10 +236,11 @@ 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(); -- 2.21.0.rc0.258.g878e2cd30e-goog