From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx48hBQld88EoogdrhwHFUZYOj22fey/+/Lphh8VRjzX5tN7wKs+H72vJfZ88pZi97AvviepY ARC-Seal: i=1; a=rsa-sha256; t=1524406694; cv=none; d=google.com; s=arc-20160816; b=UUpKJoRPwemIXBALPsTsX5FtOCkv6t6LpSnmBlgctOXPUIvnCplsuPMxcsrcEf2jY7 6zrR6hO5QMw3tpp1cfqda6Vc1O1wQu4Dv7c50pmC/heoJc7foxw54uPmJcT79jcbwp5R l6/gJe7GjQ8wXCIxCGczYP2pDfjQdh3V6OS75Tn3AshX1vT9Wn7HWjMEFGG7Hj+ptNAo +PruVLsop9KWFq3i5Ma4fdEWOdPQdoS67yhzUnkPSctMv2mJ32v5AjJhZmyXNKDKA3wu uok0XRlP1RlUuvnrFNmQQb1+LqkoKUQrtCbhb6O8RPJvJGsV9mgQvAXBpwO/nwXGFFUo 7Ohg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=G/n0qjoOvdwpyY4hLRjhExuWIqdXNCNvzGTpZJKPJSA=; b=fRmcw+za5DLmhcg+zd+5E1n8XgnAdjfZ29en1QU7qHvR/RK0O3Te35gNMVytrrdNF4 tJR+QH3d/jCFTLP7E4agEcMqsCcuybzgZ5MvtmMAHb5a81T8eIGv8T9dZ24gzHwnfmg3 dpkm5DTlKilEmhiYDfEAFGjgfQMMSGWFXCB0b9aIqmhm+e7lc6ZcDxJyPLYhj3IpiFeF pMr9iZIhdDwnKGfEFfLalStMtkenZ8tQfdwRVBa1V7FfZ/sXgJfJ9I9p/WTMTgZfFc70 NEM6VhkJIJE8qf6MCmwN8NtOyRYpee2ce+lvTmyLC9HAHRJdy1yvudFnBttvsvIE/Syp yENg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Takashi Iwai Subject: [PATCH 4.4 68/97] ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams Date: Sun, 22 Apr 2018 15:53:46 +0200 Message-Id: <20180422135308.991252429@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180422135304.577223025@linuxfoundation.org> References: <20180422135304.577223025@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1598455078261500157?= X-GMAIL-MSGID: =?utf-8?q?1598456274435466012?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 40cab6e88cb0b6c56d3f30b7491a20e803f948f6 upstream. OSS PCM stream management isn't modal but it allows ioctls issued at any time for changing the parameters. In the previous hardening patch ("ALSA: pcm: Avoid potential races between OSS ioctls and read/write"), we covered these races and prevent the corruption by protecting the concurrent accesses via params_lock mutex. However, this means that some ioctls that try to change the stream parameter (e.g. channels or format) would be blocked until the read/write finishes, and it may take really long. Basically changing the parameter while reading/writing is an invalid operation, hence it's even more user-friendly from the API POV if it returns -EBUSY in such a situation. This patch adds such checks in the relevant ioctls with the addition of read/write access refcount. Cc: Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- include/sound/pcm_oss.h | 1 + sound/core/oss/pcm_oss.c | 36 +++++++++++++++++++++++++++--------- 2 files changed, 28 insertions(+), 9 deletions(-) --- a/include/sound/pcm_oss.h +++ b/include/sound/pcm_oss.h @@ -57,6 +57,7 @@ struct snd_pcm_oss_runtime { char *buffer; /* vmallocated period */ size_t buffer_used; /* used length from period buffer */ struct mutex params_lock; + atomic_t rw_ref; /* concurrent read/write accesses */ #ifdef CONFIG_SND_PCM_OSS_PLUGINS struct snd_pcm_plugin *plugin_first; struct snd_pcm_plugin *plugin_last; --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -1404,6 +1404,7 @@ static ssize_t snd_pcm_oss_write1(struct if (atomic_read(&substream->mmap_count)) return -ENXIO; + atomic_inc(&runtime->oss.rw_ref); while (bytes > 0) { if (mutex_lock_interruptible(&runtime->oss.params_lock)) { tmp = -ERESTARTSYS; @@ -1467,6 +1468,7 @@ static ssize_t snd_pcm_oss_write1(struct } tmp = 0; } + atomic_dec(&runtime->oss.rw_ref); return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; } @@ -1512,6 +1514,7 @@ static ssize_t snd_pcm_oss_read1(struct if (atomic_read(&substream->mmap_count)) return -ENXIO; + atomic_inc(&runtime->oss.rw_ref); while (bytes > 0) { if (mutex_lock_interruptible(&runtime->oss.params_lock)) { tmp = -ERESTARTSYS; @@ -1560,6 +1563,7 @@ static ssize_t snd_pcm_oss_read1(struct } tmp = 0; } + atomic_dec(&runtime->oss.rw_ref); return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; } @@ -1666,8 +1670,11 @@ static int snd_pcm_oss_sync(struct snd_p goto __direct; if ((err = snd_pcm_oss_make_ready(substream)) < 0) return err; - if (mutex_lock_interruptible(&runtime->oss.params_lock)) + atomic_inc(&runtime->oss.rw_ref); + if (mutex_lock_interruptible(&runtime->oss.params_lock)) { + atomic_dec(&runtime->oss.rw_ref); return -ERESTARTSYS; + } format = snd_pcm_oss_format_from(runtime->oss.format); width = snd_pcm_format_physical_width(format); if (runtime->oss.buffer_used > 0) { @@ -1679,10 +1686,8 @@ static int snd_pcm_oss_sync(struct snd_p runtime->oss.buffer + runtime->oss.buffer_used, size); err = snd_pcm_oss_sync1(substream, runtime->oss.period_bytes); - if (err < 0) { - mutex_unlock(&runtime->oss.params_lock); - return err; - } + if (err < 0) + goto unlock; } else if (runtime->oss.period_ptr > 0) { #ifdef OSS_DEBUG pcm_dbg(substream->pcm, "sync: period_ptr\n"); @@ -1692,10 +1697,8 @@ static int snd_pcm_oss_sync(struct snd_p runtime->oss.buffer, size * 8 / width); err = snd_pcm_oss_sync1(substream, size); - if (err < 0) { - mutex_unlock(&runtime->oss.params_lock); - return err; - } + if (err < 0) + goto unlock; } /* * The ALSA's period might be a bit large than OSS one. @@ -1726,7 +1729,11 @@ static int snd_pcm_oss_sync(struct snd_p snd_pcm_lib_writev(substream, buffers, size); } } +unlock: mutex_unlock(&runtime->oss.params_lock); + atomic_dec(&runtime->oss.rw_ref); + if (err < 0) + return err; /* * finish sync: drain the buffer */ @@ -1774,6 +1781,8 @@ static int snd_pcm_oss_set_rate(struct s rate = 192000; if (mutex_lock_interruptible(&runtime->oss.params_lock)) return -ERESTARTSYS; + if (atomic_read(&runtime->oss.rw_ref)) + return -EBUSY; if (runtime->oss.rate != rate) { runtime->oss.params = 1; runtime->oss.rate = rate; @@ -1808,6 +1817,8 @@ static int snd_pcm_oss_set_channels(stru runtime = substream->runtime; if (mutex_lock_interruptible(&runtime->oss.params_lock)) return -ERESTARTSYS; + if (atomic_read(&runtime->oss.rw_ref)) + return -EBUSY; if (runtime->oss.channels != channels) { runtime->oss.params = 1; runtime->oss.channels = channels; @@ -1898,6 +1909,8 @@ static int snd_pcm_oss_set_format(struct if (substream == NULL) continue; runtime = substream->runtime; + if (atomic_read(&runtime->oss.rw_ref)) + return -EBUSY; if (mutex_lock_interruptible(&runtime->oss.params_lock)) return -ERESTARTSYS; if (runtime->oss.format != format) { @@ -1952,6 +1965,8 @@ static int snd_pcm_oss_set_subdivide(str if (substream == NULL) continue; runtime = substream->runtime; + if (atomic_read(&runtime->oss.rw_ref)) + return -EBUSY; if (mutex_lock_interruptible(&runtime->oss.params_lock)) return -ERESTARTSYS; err = snd_pcm_oss_set_subdivide1(substream, subdivide); @@ -1990,6 +2005,8 @@ static int snd_pcm_oss_set_fragment(stru if (substream == NULL) continue; runtime = substream->runtime; + if (atomic_read(&runtime->oss.rw_ref)) + return -EBUSY; if (mutex_lock_interruptible(&runtime->oss.params_lock)) return -ERESTARTSYS; err = snd_pcm_oss_set_fragment1(substream, val); @@ -2384,6 +2401,7 @@ static void snd_pcm_oss_init_substream(s runtime->oss.maxfrags = 0; runtime->oss.subdivision = 0; substream->pcm_release = snd_pcm_oss_release_substream; + atomic_set(&runtime->oss.rw_ref, 0); } static int snd_pcm_oss_release_file(struct snd_pcm_oss_file *pcm_oss_file)