From patchwork Mon May 31 13:13:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 450897 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 8C1C5C47083 for ; Mon, 31 May 2021 14:45:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72C4361364 for ; Mon, 31 May 2021 14:45:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230339AbhEaOrM (ORCPT ); Mon, 31 May 2021 10:47:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:40316 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234234AbhEaOpK (ORCPT ); Mon, 31 May 2021 10:45:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5AF3B61C86; Mon, 31 May 2021 13:55:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622469307; bh=e20Lmk7MCMyMXAM/WcjTRVpXTDQARr5G0Blz+3SQKm4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vP/7U8GhxhRifsytlsFBS+uTqBvwohp9Kg8pHeb/pISDrn/7zxuII+JFJ4VIqP+vQ enwASjEhX6RYWHjJY87Bie8T+l0KSDSwXVbr2z8NDGQfJikfFHvjAFUMpXWHko5oiX j/BA3zBtKe9x7ZTlEmdk9Yb9nwbFqrBuVUrgq/bI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Krzysztof Kozlowski , Wolfram Sang Subject: [PATCH 5.12 149/296] i2c: s3c2410: fix possible NULL pointer deref on read message after write Date: Mon, 31 May 2021 15:13:24 +0200 Message-Id: <20210531130708.877712547@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130703.762129381@linuxfoundation.org> References: <20210531130703.762129381@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Krzysztof Kozlowski commit 24990423267ec283b9d86f07f362b753eb9b0ed5 upstream. Interrupt handler processes multiple message write requests one after another, till the driver message queue is drained. However if driver encounters a read message without preceding START, it stops the I2C transfer as it is an invalid condition for the controller. At least the comment describes a requirement "the controller forces us to send a new START when we change direction". This stop results in clearing the message queue (i2c->msg = NULL). The code however immediately jumped back to label "retry_write" which dereferenced the "i2c->msg" making it a possible NULL pointer dereference. The Coverity analysis: 1. Condition !is_msgend(i2c), taking false branch. if (!is_msgend(i2c)) { 2. Condition !is_lastmsg(i2c), taking true branch. } else if (!is_lastmsg(i2c)) { 3. Condition i2c->msg->flags & 1, taking true branch. if (i2c->msg->flags & I2C_M_RD) { 4. write_zero_model: Passing i2c to s3c24xx_i2c_stop, which sets i2c->msg to NULL. s3c24xx_i2c_stop(i2c, -EINVAL); 5. Jumping to label retry_write. goto retry_write; 6. var_deref_model: Passing i2c to is_msgend, which dereferences null i2c->msg. if (!is_msgend(i2c)) {" All previous calls to s3c24xx_i2c_stop() in this interrupt service routine are followed by jumping to end of function (acknowledging the interrupt and returning). This seems a reasonable choice also here since message buffer was entirely emptied. Addresses-Coverity: Explicit null dereferenced Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Krzysztof Kozlowski Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/busses/i2c-s3c2410.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/i2c/busses/i2c-s3c2410.c +++ b/drivers/i2c/busses/i2c-s3c2410.c @@ -483,7 +483,10 @@ static int i2c_s3c_irq_nextbyte(struct s * forces us to send a new START * when we change direction */ + dev_dbg(i2c->dev, + "missing START before write->read\n"); s3c24xx_i2c_stop(i2c, -EINVAL); + break; } goto retry_write;