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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8971DC433EF for ; Tue, 10 May 2022 13:31:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243222AbiEJNfe (ORCPT ); Tue, 10 May 2022 09:35:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243456AbiEJNeM (ORCPT ); Tue, 10 May 2022 09:34:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57657238D75; Tue, 10 May 2022 06:24:30 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6C3D761768; Tue, 10 May 2022 13:24:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 724FEC385C2; Tue, 10 May 2022 13:24:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652189062; bh=dwo1c1VqB1TjhnB+lmO0evpTKYjAmpjBUdoni3XMw14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uG5P7bC38VJFI5zBaFd5K6kf30OwVzI3+J1FKTrNBYrNbeC3aktHoP0r92ey6A23y RZ9RflW6axqvC2Et0BiLIITkkzvZWmcmLqQZJNygytgFmfsgBiCRt2akiL1n2dBQp6 Of5rmVAr6490CjLZtFAna+ADjJUekCF3y+DdmEEQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Jaroslav Kysela , Takashi Iwai , Ovidiu Panait Subject: [PATCH 5.4 43/52] ALSA: pcm: Fix races among concurrent read/write and buffer changes Date: Tue, 10 May 2022 15:08:12 +0200 Message-Id: <20220510130731.112125943@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220510130729.852544477@linuxfoundation.org> References: <20220510130729.852544477@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Takashi Iwai commit dca947d4d26dbf925a64a6cfb2ddbc035e831a3d upstream. In the current PCM design, the read/write syscalls (as well as the equivalent ioctls) are allowed before the PCM stream is running, that is, at PCM PREPARED state. Meanwhile, we also allow to re-issue hw_params and hw_free ioctl calls at the PREPARED state that may change or free the buffers, too. The problem is that there is no protection against those mix-ups. This patch applies the previously introduced runtime->buffer_mutex to the read/write operations so that the concurrent hw_params or hw_free call can no longer interfere during the operation. The mutex is unlocked before scheduling, so we don't take it too long. Cc: Reviewed-by: Jaroslav Kysela Link: https://lore.kernel.org/r/20220322170720.3529-3-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- sound/core/pcm_lib.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1861,9 +1861,11 @@ static int wait_for_avail(struct snd_pcm if (avail >= runtime->twake) break; snd_pcm_stream_unlock_irq(substream); + mutex_unlock(&runtime->buffer_mutex); tout = schedule_timeout(wait_time); + mutex_lock(&runtime->buffer_mutex); snd_pcm_stream_lock_irq(substream); set_current_state(TASK_INTERRUPTIBLE); switch (runtime->status->state) { @@ -2157,6 +2159,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(str nonblock = !!(substream->f_flags & O_NONBLOCK); + mutex_lock(&runtime->buffer_mutex); snd_pcm_stream_lock_irq(substream); err = pcm_accessible_state(runtime); if (err < 0) @@ -2244,6 +2247,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(str if (xfer > 0 && err >= 0) snd_pcm_update_state(substream, runtime); snd_pcm_stream_unlock_irq(substream); + mutex_unlock(&runtime->buffer_mutex); return xfer > 0 ? (snd_pcm_sframes_t)xfer : err; } EXPORT_SYMBOL(__snd_pcm_lib_xfer);