From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B27CDC433DF for ; Tue, 9 Jun 2020 04:35:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6F87B20812 for ; Tue, 9 Jun 2020 04:35:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Z17XfRAc" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F87B20812 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1C8058D0025; Tue, 9 Jun 2020 00:35:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 19E458D0011; Tue, 9 Jun 2020 00:35:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 066CC8D0025; Tue, 9 Jun 2020 00:35:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0069.hostedemail.com [216.40.44.69]) by kanga.kvack.org (Postfix) with ESMTP id DE6DB8D0011 for ; Tue, 9 Jun 2020 00:35:06 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id B4C2A3561 for ; Tue, 9 Jun 2020 04:35:06 +0000 (UTC) X-FDA: 76908408612.22.look62_0c1565826dbf Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 9166018038E6A for ; Tue, 9 Jun 2020 04:35:06 +0000 (UTC) X-HE-Tag: look62_0c1565826dbf X-Filterd-Recvd-Size: 4373 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Tue, 9 Jun 2020 04:35:06 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 116D3208A7; Tue, 9 Jun 2020 04:35:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591677305; bh=sLLncrYtf4oTgN55eEa8RCixEMt3kTEdOzD36w0Z2NQ=; h=Date:From:To:Subject:In-Reply-To:From; b=Z17XfRAcW0eoHg6H9mZKMFpL2pVJnEoKL68jzRyuMS68W6q9TqJOyTnwNWgHWN6ZI eUMOo5RUl6cd09EfYwwoHy8PzMaWPAGnKQohzbSrSf/dCgM0TBoOvaVhdoR03fRzRq TlEXbU9tv3WIgtymP+8lzyrikcJsDth+72TeX2NQ= Date: Mon, 08 Jun 2020 21:35:04 -0700 From: Andrew Morton To: akpm@linux-foundation.org, ast@kernel.org, daniel@iogearbox.net, hch@lst.de, hpa@zytor.com, linux-mm@kvack.org, mhiramat@kernel.org, mingo@elte.hu, mm-commits@vger.kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org Subject: [patch 92/93] maccess: return -ERANGE when probe_kernel_read() fails Message-ID: <20200609043504.wIFXLLZEu%akpm@linux-foundation.org> In-Reply-To: <20200608212922.5b7fa74ca3f4e2444441b7f9@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 9166018038E6A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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: From: Christoph Hellwig Subject: maccess: return -ERANGE when probe_kernel_read() fails Allow the callers to distinguish a real unmapped address vs a range that can't be probed. Link: http://lkml.kernel.org/r/20200521152301.2587579-24-hch@lst.de Signed-off-by: Christoph Hellwig Suggested-by: Masami Hiramatsu Reviewed-by: Masami Hiramatsu Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- mm/maccess.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) --- a/mm/maccess.c~maccess-return-erange-when-copy_from_kernel_nofault_allowed-fails +++ a/mm/maccess.c @@ -24,7 +24,7 @@ bool __weak probe_kernel_read_allowed(co long probe_kernel_read(void *dst, const void *src, size_t size) { if (!probe_kernel_read_allowed(src, size)) - return -EFAULT; + return -ERANGE; pagefault_disable(); probe_kernel_read_loop(dst, src, size, u64, Efault); @@ -68,7 +68,7 @@ long strncpy_from_kernel_nofault(char *d if (unlikely(count <= 0)) return 0; if (!probe_kernel_read_allowed(unsafe_addr, count)) - return -EFAULT; + return -ERANGE; pagefault_disable(); do { @@ -93,7 +93,8 @@ Efault: * @size: size of the data chunk * * Safely read from kernel address @src to the buffer at @dst. If a kernel - * fault happens, handle that and return -EFAULT. + * fault happens, handle that and return -EFAULT. If @src is not a valid kernel + * address, return -ERANGE. * * We ensure that the copy_from_user is executed in atomic context so that * do_page_fault() doesn't attempt to take mmap_lock. This makes @@ -106,7 +107,7 @@ long probe_kernel_read(void *dst, const mm_segment_t old_fs = get_fs(); if (!probe_kernel_read_allowed(src, size)) - return -EFAULT; + return -ERANGE; set_fs(KERNEL_DS); pagefault_disable(); @@ -158,8 +159,9 @@ long probe_kernel_write(void *dst, const * * On success, returns the length of the string INCLUDING the trailing NUL. * - * If access fails, returns -EFAULT (some data may have been copied - * and the trailing NUL added). + * If access fails, returns -EFAULT (some data may have been copied and the + * trailing NUL added). If @unsafe_addr is not a valid kernel address, return + * -ERANGE. * * If @count is smaller than the length of the string, copies @count-1 bytes, * sets the last byte of @dst buffer to NUL and returns @count. @@ -173,7 +175,7 @@ long strncpy_from_kernel_nofault(char *d if (unlikely(count <= 0)) return 0; if (!probe_kernel_read_allowed(unsafe_addr, count)) - return -EFAULT; + return -ERANGE; set_fs(KERNEL_DS); pagefault_disable(); _