From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752007AbbJLJW7 (ORCPT ); Mon, 12 Oct 2015 05:22:59 -0400 Received: from mail.skyhub.de ([78.46.96.112]:46015 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751842AbbJLJW4 (ORCPT ); Mon, 12 Oct 2015 05:22:56 -0400 From: Borislav Petkov To: Ingo Molnar Cc: LKML Subject: [PATCH 2/6] x86/ras/mce_amd_inj: Return early on invalid input Date: Mon, 12 Oct 2015 11:22:38 +0200 Message-Id: <1444641762-9437-3-git-send-email-bp@alien8.de> X-Mailer: git-send-email 2.3.5 In-Reply-To: <1444641762-9437-1-git-send-email-bp@alien8.de> References: <1444641762-9437-1-git-send-email-bp@alien8.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Aravind Gopalakrishnan Invalid inputs such as these are currently reported in dmesg as failing: $> echo sweet > flags [ 122.079139] flags_write: Invalid flags value: et even though the 'flags' attribute has been updated correctly: $> cat flags sw This is because userspace keeps writing the remaining buffer until it encounters an error. However, the input as a whole is wrong and we should not be writing anything to the file. Therefore, correct flags_write() to return -EINVAL immediately on bad input strings. Signed-off-by: Aravind Gopalakrishnan Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Thomas Gleixner Cc: x86-ml Link: http://lkml.kernel.org/r/1443190851-2172-2-git-send-email-Aravind.Gopalakrishnan@amd.com Signed-off-by: Borislav Petkov --- arch/x86/ras/mce_amd_inj.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/x86/ras/mce_amd_inj.c b/arch/x86/ras/mce_amd_inj.c index 17e35b5bf779..4fd8bb9b90b9 100644 --- a/arch/x86/ras/mce_amd_inj.c +++ b/arch/x86/ras/mce_amd_inj.c @@ -129,12 +129,9 @@ static ssize_t flags_write(struct file *filp, const char __user *ubuf, { char buf[MAX_FLAG_OPT_SIZE], *__buf; int err; - size_t ret; if (cnt > MAX_FLAG_OPT_SIZE) - cnt = MAX_FLAG_OPT_SIZE; - - ret = cnt; + return -EINVAL; if (copy_from_user(&buf, ubuf, cnt)) return -EFAULT; @@ -150,9 +147,9 @@ static ssize_t flags_write(struct file *filp, const char __user *ubuf, return err; } - *ppos += ret; + *ppos += cnt; - return ret; + return cnt; } static const struct file_operations flags_fops = { -- 2.3.5