From patchwork Wed May 26 12:39:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krzysztof Kozlowski X-Patchwork-Id: 448494 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 49C23C4708A for ; Wed, 26 May 2021 12:39:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F5AA613D6 for ; Wed, 26 May 2021 12:39:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232367AbhEZMlV (ORCPT ); Wed, 26 May 2021 08:41:21 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56619 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234469AbhEZMlR (ORCPT ); Wed, 26 May 2021 08:41:17 -0400 Received: from mail-vs1-f71.google.com ([209.85.217.71]) by youngberry.canonical.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1llsp6-00007l-GT for linux-i2c@vger.kernel.org; Wed, 26 May 2021 12:39:44 +0000 Received: by mail-vs1-f71.google.com with SMTP id x2-20020a67c0820000b0290231d255cecdso187281vsi.4 for ; Wed, 26 May 2021 05:39:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=gN2u9zXldM21EHt67+sMR5HlACJwh4tvgZXmS6a8P94=; b=T+I5DpZhXmOLQWzRA82Iwo8Miy560fmBYr3QnS1tVFb9nfotWMYKGi1k1VyR3CuTz7 cAt+i69I9NXSFOf0c0zqutpQZZudOMyARGrnagUZYDV1VUgghIoxNFktA8T5bEiT8Atg Eq794DL/V2xSgwo8m9REHuB+dxIOVrKEkklq7cVJnHFZlnQ1K2ImRKmkEtTDsymiBEay oi8HPqgWj03n+G4Mn4Xyvjjjv4ZsVRcaErlABWtHFJJN7rvdfgTMqj7lMuG0DgRUumQw 3x7iKwnkzMgp5YE4Ysjaro6Cne61q59Zk/5+KkNmuzZtB4whr6ynmkVmglNfBdPd+prn 2pXQ== X-Gm-Message-State: AOAM533emm3U0ea/TwSq2u10namLKG4Jky1yROcW9GIj+jhPgWT+NqCr uU9EBRU3ihb1ZTR85S1K7Y4BAxZDHRoPCewRljL6zvWqhfh+7RBkypdgki7I4BlKXK+Ve3c6sRH bL+li85oMtrhIunuwGBL3m+GLibE9IIPFxMnC5w== X-Received: by 2002:ab0:5acf:: with SMTP id x15mr32137315uae.132.1622032783581; Wed, 26 May 2021 05:39:43 -0700 (PDT) X-Google-Smtp-Source: ABdhPJw/SfZLr/bmF5flVczWQ9oLy5YTXK6WvySQPDkCj5uV/aFtLdOjVhbvV6qeYmmthiflkK7Q7Q== X-Received: by 2002:ab0:5acf:: with SMTP id x15mr32137298uae.132.1622032783424; Wed, 26 May 2021 05:39:43 -0700 (PDT) Received: from localhost.localdomain ([45.237.48.4]) by smtp.gmail.com with ESMTPSA id n77sm1693475vke.24.2021.05.26.05.39.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 May 2021 05:39:42 -0700 (PDT) From: Krzysztof Kozlowski To: Krzysztof Kozlowski , linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Marek Szyprowski , Sylwester Nawrocki , Bartlomiej Zolnierkiewicz , Tomasz Figa Subject: [RESEND PATCH] i2c: s3c2410: fix possible NULL pointer deref on read message after write Date: Wed, 26 May 2021 08:39:37 -0400 Message-Id: <20210526123937.22958-1-krzysztof.kozlowski@canonical.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org 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 --- Reason for resend - the patch did not get necessary testing however I think it is correct, therefore resending without "RFT". --- drivers/i2c/busses/i2c-s3c2410.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c index ab928613afba..4d82761e1585 100644 --- a/drivers/i2c/busses/i2c-s3c2410.c +++ b/drivers/i2c/busses/i2c-s3c2410.c @@ -480,7 +480,10 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat) * 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;