From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752833AbeDRARH (ORCPT ); Tue, 17 Apr 2018 20:17:07 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:41130 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751878AbeDRARG (ORCPT ); Tue, 17 Apr 2018 20:17:06 -0400 X-Google-Smtp-Source: AIpwx4+bLH2J2gfjxwSHIVADmPF30mb4nGOOxwR+AIf2/D+EPp+TRdP/Wcpf2b60CdEuSgyA7x9uaw== From: Alexander Popov To: Wolfram Sang , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, sil2review@lists.osadl.org, Dmitry Vyukov , Alexander Popov Subject: [PATCH 1/1] i2c: dev: check i2c_msg len before memdup_user() to prevent ZERO_SIZE_PTR deref Date: Wed, 18 Apr 2018 03:16:45 +0300 Message-Id: <1524010605-21552-1-git-send-email-alex.popov@linux.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently i2cdev_ioctl_rdwr() doesn't check i2c_msg len against zero before calling memdup_user(). If this len is zero memdup_user() returns ZERO_SIZE_PTR, which is later considered as valid since IS_ERR(ZERO_SIZE_PTR) is false. That causes ZERO_SIZE_PTR deref oops. Let's check i2c_msg len against zero before calling memdup_user(). This issue was triggered by syzkaller. Signed-off-by: Alexander Popov --- drivers/i2c/i2c-dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index 036a03f..b9b6715 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -252,8 +252,8 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client, res = 0; for (i = 0; i < nmsgs; i++) { - /* Limit the size of the message to a sane amount */ - if (msgs[i].len > 8192) { + /* Check that the size is sane */ + if (!msgs[i].len || msgs[i].len > 8192) { res = -EINVAL; break; } -- 2.7.4