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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 6383DC433E0 for ; Thu, 30 Jul 2020 08:19:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 321362075F for ; Thu, 30 Jul 2020 08:19:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596097145; bh=N9rfu8Rm9dG6SIRtmK83SO4PfCqaxsXzeswlY0y/zTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MupZwTgfflqvEVFdIF5/sy4ZVkxF+popxK17K8xfBBEOoigqIrBhU21xEOo1KtrIn qOoFJx7OO4U+Bcp2HiSqsqh1/NAnUs44iM1zEkTXivBm/yAbyqaAg3Q0gnLDD9wu4/ s1qEgj8KUT0JqzhGLeoXtDAwIKOycmLEDx25RCZE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729855AbgG3ITD (ORCPT ); Thu, 30 Jul 2020 04:19:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:46558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729004AbgG3IIU (ORCPT ); Thu, 30 Jul 2020 04:08:20 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1D46320842; Thu, 30 Jul 2020 08:08:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596096499; bh=N9rfu8Rm9dG6SIRtmK83SO4PfCqaxsXzeswlY0y/zTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JJTy3DKBrg+di7WcHjitRd4Ojc+5IbscxcSOXibP9FudtA8+pdUQtNdIPfAOKvR1H wBFic6elax/IiTm0pWQFzPHYlvtzuxssHhXv6uJvO2YQxDNu8cgiUNnq1XUEByPpyO S1Jap+9UP6q3SiVJ3yptmmkmUt5wRf6tBjdW+qE0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+e42d0746c3c3699b6061@syzkaller.appspotmail.com, Takashi Iwai Subject: [PATCH 4.9 11/61] ALSA: info: Drop WARN_ON() from buffer NULL sanity check Date: Thu, 30 Jul 2020 10:04:29 +0200 Message-Id: <20200730074421.372273466@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200730074420.811058810@linuxfoundation.org> References: <20200730074420.811058810@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Takashi Iwai commit 60379ba08532eca861e933b389526a4dc89e0c42 upstream. snd_info_get_line() has a sanity check of NULL buffer -- both buffer itself being NULL and buffer->buffer being NULL. Basically both checks are valid and necessary, but the problem is that it's with snd_BUG_ON() macro that triggers WARN_ON(). The latter condition (NULL buffer->buffer) can be met arbitrarily by user since the buffer is allocated at the first write, so it means that user can trigger WARN_ON() at will. This patch addresses it by simply moving buffer->buffer NULL check out of snd_BUG_ON() so that spurious WARNING is no longer triggered. Reported-by: syzbot+e42d0746c3c3699b6061@syzkaller.appspotmail.com Cc: Link: https://lore.kernel.org/r/20200717084023.5928-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/info.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/sound/core/info.c +++ b/sound/core/info.c @@ -634,7 +634,9 @@ int snd_info_get_line(struct snd_info_bu { int c = -1; - if (snd_BUG_ON(!buffer || !buffer->buffer)) + if (snd_BUG_ON(!buffer)) + return 1; + if (!buffer->buffer) return 1; if (len <= 0 || buffer->stop || buffer->error) return 1;