Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753442AbdGPO0d (ORCPT ); Sun, 16 Jul 2017 10:26:33 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44258 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753278AbdGPOPb (ORCPT ); Sun, 16 Jul 2017 10:15:31 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Al Viro" , "James Hogan" , linux-metag@vger.kernel.org Date: Sun, 16 Jul 2017 14:56:46 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 130/178] metag/usercopy: Add early abort to copy_to_user In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2427 Lines: 101 3.16.46-rc1 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: Ben Hutchings --- 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);