Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 02 Nov 2018 08:42:10 +0100
Message-ID: <s5htvl0exil.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     Rohit kumar <rohitkr@codeaurora.org>
Cc:     plai@codeaurora.org, bgoswami@codeaurora.org, lgirdwood@gmail.com,
        broonie@kernel.org, perex@perex.cz, tiwai@suse.com,
        alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        rohkumar@qti.qualcomm.com, srinivas.kandagatla@linaro.org
Subject: Re: [alsa-devel] [PATCH] ASoC: core: Invoke pcm_new() for all DAI-link
In-Reply-To: <1541075929-29323-1-git-send-email-rohitkr@codeaurora.org>
References: <1541075929-29323-1-git-send-email-rohitkr@codeaurora.org>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka)
 FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/26
 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka")
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, 01 Nov 2018 13:38:49 +0100,
Rohit kumar wrote:
> 
> Remove no_pcm check to invoke pcm_new() for backend dai-links
> too. This fixes crash in hdmi codec driver during hdmi_codec_startup()
> while accessing chmap_info struct. chmap_info struct memory is
> allocated in pcm_new() of hdmi codec driver which is not invoked
> in case of DPCM when hdmi codec driver is part of backend dai-link.
> 
> Below is the crash stack:
> 
> [   61.635493] Unable to handle kernel NULL pointer dereference at virtual address 00000018
> ..
> [   61.666696]   CM = 0, WnR = 1
> [   61.669778] user pgtable: 4k pages, 39-bit VAs, pgd = ffffffc0d6633000
> [   61.676526] [0000000000000018] *pgd=0000000153fc8003, *pud=0000000153fc8003, *pmd=0000000000000000
> [   61.685793] Internal error: Oops: 96000046 [#1] PREEMPT SMP
> [   61.722955] CPU: 7 PID: 2238 Comm: aplay Not tainted 4.14.72 #21
> ..
> [   61.740269] PC is at hdmi_codec_startup+0x124/0x164
> [   61.745308] LR is at hdmi_codec_startup+0xe4/0x164
> 
> Signed-off-by: Rohit kumar <rohitkr@codeaurora.org>

Did you check whether all drivers have no side-effect by this change?
The hdmi-codec isn't the only driver that has pcm_new ops, so we have
to make sure that such a fundamental change wouldn't bring any
regressions.


thanks,

Takashi