From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 DD9DFC7618B for ; Tue, 23 Jul 2019 13:40:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B1FAC218D4 for ; Tue, 23 Jul 2019 13:40:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="htZKGSZg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390350AbfGWNkd (ORCPT ); Tue, 23 Jul 2019 09:40:33 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:37104 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390330AbfGWNk1 (ORCPT ); Tue, 23 Jul 2019 09:40:27 -0400 Received: by mail-pf1-f194.google.com with SMTP id 19so19174196pfa.4 for ; Tue, 23 Jul 2019 06:40:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=jugRb2vt232DJ0Tf9bLWXh+Q8rg8VA+VLd86FZGf/5M=; b=htZKGSZgs7EAS6bHJHCCD1rlhs+g8kjPbkcAjHDjjnVRqUXoJ/Op7Nc8H/+IN4uKHK 41NySenxDvpM4uOPOzcGBovI94jHxhaiHYI4P9ILZpM9swPw9CFPT9M3XoKf4auraunj cKxA4D0m1M3ZukOiqFvDsxYOmNYOOg3Ftv6DvBN9Gou3MP/QZPdwQtHmbtA+JDKLIV9b QfznGZ8dq7j44JmbcM48IYAldcSLRBcQ283zrv21VxAh9rNYiAvlbRQ36EP7Rk4DFvio pu3bzJcO6i/1PuOi20iHkvNQQPnsbhpLwIvXbOk8/vj8cF44m3BlwcGGDMSRyMS2jiZY lZKA== 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; bh=jugRb2vt232DJ0Tf9bLWXh+Q8rg8VA+VLd86FZGf/5M=; b=YWeVGjPRvogh072r2UKnduYvrvRfUZoF9ru5m7zJTwusnmwNQ6pikuPB02xgtxNjYw V7ificzo0lvyxwhaXCmoseYwDAsH8MenvDXFPZWm6f7NrdXDOvjA3lrxNSPf/H8o1XeZ GH3tjK6yoP/REqHH3O2yB8fccME5Oj20yS3YcrzOuu4wB42REJvvl9muscvJ1Nv6uhIV FrKwHg3BgbVLBQoy+e6tegx2JWSLVMSi6cEHshqxh6FyIc4ZOR5f1/4zSrsU5MeXmekx bRu7kWkTzDWwWDmM/WaAghlf1NkgGrsStFWxSggUrQJOvvEIqCiiY+FkNGiY6yeNn+1q jVqA== X-Gm-Message-State: APjAAAXS7VQrEqG1YY/qX6J95EaMXH83Sw1D+9c+nyD42ZA9Rc2eXXG2 Xc2UnNxk64J8lFIx+PNR16I= X-Google-Smtp-Source: APXvYqy8VT8V/nFcsrgzWFDj6Z0IY9HPcv+uKoEjpRhDzmbL3rSCPKiqORlzVCMoErFHH2h5eRopMA== X-Received: by 2002:a17:90a:9903:: with SMTP id b3mr81880307pjp.80.1563889226916; Tue, 23 Jul 2019 06:40:26 -0700 (PDT) Received: from oslab.tsinghua.edu.cn ([2402:f000:4:72:808::3ca]) by smtp.gmail.com with ESMTPSA id d6sm37813630pgf.55.2019.07.23.06.40.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jul 2019 06:40:26 -0700 (PDT) From: Jia-Ju Bai To: perex@perex.cz, tiwai@suse.com, huangfq.daxian@gmail.com, tglx@linutronix.de, allison@lohutok.net Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH] ALSA: isa: gus: Fix a possible null-pointer dereference in snd_gf1_mem_xfree() Date: Tue, 23 Jul 2019 21:40:20 +0800 Message-Id: <20190723134020.25972-1-baijiaju1990@gmail.com> X-Mailer: git-send-email 2.17.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In snd_gf1_mem_xfree(), there is an if statement on line 72 and line 74 to check whether block->next is NULL: if (block->next) When block->next is NULL, block->next is used on line 84: block->next->prev = block->prev; Thus, a possible null-pointer dereference may occur in this case. To fix this possible bug, block->next is checked before using it. This bug is found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai --- sound/isa/gus/gus_mem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sound/isa/gus/gus_mem.c b/sound/isa/gus/gus_mem.c index cb02d18dde60..ed6205b88057 100644 --- a/sound/isa/gus/gus_mem.c +++ b/sound/isa/gus/gus_mem.c @@ -81,7 +81,8 @@ int snd_gf1_mem_xfree(struct snd_gf1_mem * alloc, struct snd_gf1_mem_block * blo if (block->prev) block->prev->next = NULL; } else { - block->next->prev = block->prev; + if (block->next) + block->next->prev = block->prev; if (block->prev) block->prev->next = block->next; } -- 2.17.0