From patchwork Sat Dec 19 12:58:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 346242 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, URIBL_BLOCKED, 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 B90BEC0018C for ; Sat, 19 Dec 2020 13:01:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8ECC72388E for ; Sat, 19 Dec 2020 13:01:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728235AbgLSM7f (ORCPT ); Sat, 19 Dec 2020 07:59:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:46570 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728229AbgLSM7e (ORCPT ); Sat, 19 Dec 2020 07:59:34 -0500 From: Greg Kroah-Hartman Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+df7dc146ebdd6435eea3@syzkaller.appspotmail.com, Takashi Iwai Subject: [PATCH 5.9 44/49] ALSA: pcm: oss: Fix potential out-of-bounds shift Date: Sat, 19 Dec 2020 13:58:48 +0100 Message-Id: <20201219125346.823690385@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201219125344.671832095@linuxfoundation.org> References: <20201219125344.671832095@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Takashi Iwai commit 175b8d89fe292796811fdee87fa39799a5b6b87a upstream. syzbot spotted a potential out-of-bounds shift in the PCM OSS layer where it calculates the buffer size with the arbitrary shift value given via an ioctl. Add a range check for avoiding the undefined behavior. As the value can be treated by a signed integer, the max shift should be 30. Reported-by: syzbot+df7dc146ebdd6435eea3@syzkaller.appspotmail.com Cc: Link: https://lore.kernel.org/r/20201209084552.17109-2-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/oss/pcm_oss.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -1935,11 +1935,15 @@ static int snd_pcm_oss_set_subdivide(str static int snd_pcm_oss_set_fragment1(struct snd_pcm_substream *substream, unsigned int val) { struct snd_pcm_runtime *runtime; + int fragshift; runtime = substream->runtime; if (runtime->oss.subdivision || runtime->oss.fragshift) return -EINVAL; - runtime->oss.fragshift = val & 0xffff; + fragshift = val & 0xffff; + if (fragshift >= 31) + return -EINVAL; + runtime->oss.fragshift = fragshift; runtime->oss.maxfrags = (val >> 16) & 0xffff; if (runtime->oss.fragshift < 4) /* < 16 */ runtime->oss.fragshift = 4;