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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20D1FC433F5 for ; Sat, 13 Nov 2021 13:07:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0BDD60724 for ; Sat, 13 Nov 2021 13:07:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235634AbhKMNKb (ORCPT ); Sat, 13 Nov 2021 08:10:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:49812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234327AbhKMNKb (ORCPT ); Sat, 13 Nov 2021 08:10:31 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8AA9460551; Sat, 13 Nov 2021 13:07:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636808859; bh=XvwkcrqtNUjP+6V7N4S5ryJi6eTyIZFdmrnnRhFUwyQ=; h=Subject:To:Cc:From:Date:From; b=zN/ThispN/Dl1WVxK7+3Imh0wOxtof8JNvhsBpo61dekzJp6vREkCefLSvDxc62K/ JE9brbnfZz6jxzjQKb3rSPc/PQ3c/Nl5MF7XsL7H8dgaNyS10T4KZkyZ2CrsutpvzC OHTMp8D2sRSZAXx0Rq13SPePsF5tli7nqJErmmvg= Subject: FAILED: patch "[PATCH] ALSA: mixer: oss: Fix racy access to slots" failed to apply to 5.4-stable tree To: tiwai@suse.de, perex@perex.cz, stable@vger.kernel.org Cc: From: Date: Sat, 13 Nov 2021 14:07:36 +0100 Message-ID: <1636808856212159@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 411cef6adfb38a5bb6bd9af3941b28198e7fb680 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Wed, 20 Oct 2021 18:48:46 +0200 Subject: [PATCH] ALSA: mixer: oss: Fix racy access to slots The OSS mixer can reassign the mapping slots dynamically via proc file. Although the addition and deletion of those slots are protected by mixer->reg_mutex, the access to slots aren't, hence this may cause UAF when the slots in use are deleted concurrently. This patch applies the mixer->reg_mutex in all appropriate code paths (i.e. the ioctl functions) that may access slots. Reported-by: syzbot+9988f17cf72a1045a189@syzkaller.appspotmail.com Reviewed-by: Jaroslav Kysela Cc: Link: https://lore.kernel.org/r/00000000000036adc005ceca9175@google.com Link: https://lore.kernel.org/r/20211020164846.922-1-tiwai@suse.de Signed-off-by: Takashi Iwai diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c index 6a5abdd4271b..d5ddc154a735 100644 --- a/sound/core/oss/mixer_oss.c +++ b/sound/core/oss/mixer_oss.c @@ -130,11 +130,13 @@ static int snd_mixer_oss_devmask(struct snd_mixer_oss_file *fmixer) if (mixer == NULL) return -EIO; + mutex_lock(&mixer->reg_mutex); for (chn = 0; chn < 31; chn++) { pslot = &mixer->slots[chn]; if (pslot->put_volume || pslot->put_recsrc) result |= 1 << chn; } + mutex_unlock(&mixer->reg_mutex); return result; } @@ -146,11 +148,13 @@ static int snd_mixer_oss_stereodevs(struct snd_mixer_oss_file *fmixer) if (mixer == NULL) return -EIO; + mutex_lock(&mixer->reg_mutex); for (chn = 0; chn < 31; chn++) { pslot = &mixer->slots[chn]; if (pslot->put_volume && pslot->stereo) result |= 1 << chn; } + mutex_unlock(&mixer->reg_mutex); return result; } @@ -161,6 +165,7 @@ static int snd_mixer_oss_recmask(struct snd_mixer_oss_file *fmixer) if (mixer == NULL) return -EIO; + mutex_lock(&mixer->reg_mutex); if (mixer->put_recsrc && mixer->get_recsrc) { /* exclusive */ result = mixer->mask_recsrc; } else { @@ -172,6 +177,7 @@ static int snd_mixer_oss_recmask(struct snd_mixer_oss_file *fmixer) result |= 1 << chn; } } + mutex_unlock(&mixer->reg_mutex); return result; } @@ -182,12 +188,12 @@ static int snd_mixer_oss_get_recsrc(struct snd_mixer_oss_file *fmixer) if (mixer == NULL) return -EIO; + mutex_lock(&mixer->reg_mutex); if (mixer->put_recsrc && mixer->get_recsrc) { /* exclusive */ - int err; unsigned int index; - err = mixer->get_recsrc(fmixer, &index); - if (err < 0) - return err; + result = mixer->get_recsrc(fmixer, &index); + if (result < 0) + goto unlock; result = 1 << index; } else { struct snd_mixer_oss_slot *pslot; @@ -202,7 +208,10 @@ static int snd_mixer_oss_get_recsrc(struct snd_mixer_oss_file *fmixer) } } } - return mixer->oss_recsrc = result; + mixer->oss_recsrc = result; + unlock: + mutex_unlock(&mixer->reg_mutex); + return result; } static int snd_mixer_oss_set_recsrc(struct snd_mixer_oss_file *fmixer, int recsrc) @@ -215,6 +224,7 @@ static int snd_mixer_oss_set_recsrc(struct snd_mixer_oss_file *fmixer, int recsr if (mixer == NULL) return -EIO; + mutex_lock(&mixer->reg_mutex); if (mixer->get_recsrc && mixer->put_recsrc) { /* exclusive input */ if (recsrc & ~mixer->oss_recsrc) recsrc &= ~mixer->oss_recsrc; @@ -240,6 +250,7 @@ static int snd_mixer_oss_set_recsrc(struct snd_mixer_oss_file *fmixer, int recsr } } } + mutex_unlock(&mixer->reg_mutex); return result; } @@ -251,6 +262,7 @@ static int snd_mixer_oss_get_volume(struct snd_mixer_oss_file *fmixer, int slot) if (mixer == NULL || slot > 30) return -EIO; + mutex_lock(&mixer->reg_mutex); pslot = &mixer->slots[slot]; left = pslot->volume[0]; right = pslot->volume[1]; @@ -258,15 +270,21 @@ static int snd_mixer_oss_get_volume(struct snd_mixer_oss_file *fmixer, int slot) result = pslot->get_volume(fmixer, pslot, &left, &right); if (!pslot->stereo) right = left; - if (snd_BUG_ON(left < 0 || left > 100)) - return -EIO; - if (snd_BUG_ON(right < 0 || right > 100)) - return -EIO; + if (snd_BUG_ON(left < 0 || left > 100)) { + result = -EIO; + goto unlock; + } + if (snd_BUG_ON(right < 0 || right > 100)) { + result = -EIO; + goto unlock; + } if (result >= 0) { pslot->volume[0] = left; pslot->volume[1] = right; result = (left & 0xff) | ((right & 0xff) << 8); } + unlock: + mutex_unlock(&mixer->reg_mutex); return result; } @@ -279,6 +297,7 @@ static int snd_mixer_oss_set_volume(struct snd_mixer_oss_file *fmixer, if (mixer == NULL || slot > 30) return -EIO; + mutex_lock(&mixer->reg_mutex); pslot = &mixer->slots[slot]; if (left > 100) left = 100; @@ -289,10 +308,13 @@ static int snd_mixer_oss_set_volume(struct snd_mixer_oss_file *fmixer, if (pslot->put_volume) result = pslot->put_volume(fmixer, pslot, left, right); if (result < 0) - return result; + goto unlock; pslot->volume[0] = left; pslot->volume[1] = right; - return (left & 0xff) | ((right & 0xff) << 8); + result = (left & 0xff) | ((right & 0xff) << 8); + unlock: + mutex_lock(&mixer->reg_mutex); + return result; } static int snd_mixer_oss_ioctl1(struct snd_mixer_oss_file *fmixer, unsigned int cmd, unsigned long arg)