From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755547AbdDJRMt (ORCPT ); Mon, 10 Apr 2017 13:12:49 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36118 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932191AbdDJQvO (ORCPT ); Mon, 10 Apr 2017 12:51:14 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro , James Hogan , linux-metag@vger.kernel.org Subject: [PATCH 4.10 036/110] metag/usercopy: Add early abort to copy_to_user Date: Mon, 10 Apr 2017 18:42:27 +0200 Message-Id: <20170410164203.242242037@linuxfoundation.org> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170410164201.247583164@linuxfoundation.org> References: <20170410164201.247583164@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Hogan commit fb8ea062a8f2e85256e13f55696c5c5f0dfdcc8b upstream. When copying to userland on Meta, if any faults are encountered immediately abort the copy instead of continuing on and repeatedly faulting, and worse potentially copying further bytes successfully to subsequent valid pages. Fixes: 373cd784d0fc ("metag: Memory handling") Reported-by: Al Viro Signed-off-by: James Hogan Cc: linux-metag@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- arch/metag/lib/usercopy.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) --- a/arch/metag/lib/usercopy.c +++ b/arch/metag/lib/usercopy.c @@ -538,23 +538,31 @@ unsigned long __copy_user(void __user *p if ((unsigned long) src & 1) { __asm_copy_to_user_1(dst, src, retn); n--; + if (retn) + return retn + n; } if ((unsigned long) dst & 1) { /* Worst case - byte copy */ while (n > 0) { __asm_copy_to_user_1(dst, src, retn); n--; + if (retn) + return retn + n; } } if (((unsigned long) src & 2) && n >= 2) { __asm_copy_to_user_2(dst, src, retn); n -= 2; + if (retn) + return retn + n; } if ((unsigned long) dst & 2) { /* Second worst case - word copy */ while (n >= 2) { __asm_copy_to_user_2(dst, src, retn); n -= 2; + if (retn) + return retn + n; } } @@ -569,6 +577,8 @@ unsigned long __copy_user(void __user *p while (n >= 8) { __asm_copy_to_user_8x64(dst, src, retn); n -= 8; + if (retn) + return retn + n; } } if (n >= RAPF_MIN_BUF_SIZE) { @@ -581,6 +591,8 @@ unsigned long __copy_user(void __user *p while (n >= 8) { __asm_copy_to_user_8x64(dst, src, retn); n -= 8; + if (retn) + return retn + n; } } #endif @@ -588,11 +600,15 @@ unsigned long __copy_user(void __user *p while (n >= 16) { __asm_copy_to_user_16(dst, src, retn); n -= 16; + if (retn) + return retn + n; } while (n >= 4) { __asm_copy_to_user_4(dst, src, retn); n -= 4; + if (retn) + return retn + n; } switch (n) { @@ -609,6 +625,10 @@ unsigned long __copy_user(void __user *p break; } + /* + * If we get here, retn correctly reflects the number of failing + * bytes. + */ return retn; } EXPORT_SYMBOL(__copy_user);