linux-kernel - Re: [PATCH] soc: mediatek: cmdq: avoid racing condition with mutex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1577671361.8160.2.camel@mtksdaap41>
Date:   Mon, 30 Dec 2019 10:02:41 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Bibby Hsieh <bibby.hsieh@...iatek.com>
CC:     Jassi Brar <jassisinghbrar@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>,
        Nicolas Boichat <drinkcat@...omium.org>,
        Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>,
        Houlong Wei <houlong.wei@...iatek.com>
Subject: Re: [PATCH] soc: mediatek: cmdq: avoid racing condition with mutex

Hi, Jassi:

Ping again.

Are mbox_send_message() and mbox_client_txdone() thread-safe? If these
two are thread-safe, this bug should be fixed in mailbox core not
client.

Regards,
CK

On Wed, 2019-12-04 at 10:22 +0800, CK Hu wrote:
> Hi, Jassi:
> 
> Are mbox_send_message() and mbox_client_txdone() thread-safe? If these
> two are thread-safe, this bug should be fixed in mailbox core not
> client.
> 
> Regards,
> CK
> 
> On Thu, 2019-11-21 at 15:29 +0800, Bibby Hsieh wrote:
> > If cmdq client is multi thread user, racing will occur without mutex
> > protection. It will make the C message queued in mailbox's queue
> > always need D message's triggering.
> > 
> > Thread A		Thread B		  Thread C		Thread D...
> > -----------------------------------------------------------------------------------
> > mbox_send_message()
> > 	send_data()
> > 			mbox_send_message()
> > 				*exit
> > 						mbox_send_message()
> > 							*exit
> > mbox_client_txdone()
> > 	tx_tick()
> > 			mbox_client_txdone()
> > 				tx_tick()
> > 						mbox_client_txdone()
> > 							tx_tick()
> > msg_submit()
> > 	send_data()
> > 			msg_submit()
> > 				*exit
> > 						msg_submit()
> > 							*exit
> > -----------------------------------------------------------------------------------
> > 
> > Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
> > ---
> >  drivers/soc/mediatek/mtk-cmdq-helper.c | 3 +++
> >  include/linux/soc/mediatek/mtk-cmdq.h  | 1 +
> >  2 files changed, 4 insertions(+)
> > 
> > diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > index 9add0fd5fa6c..9e35e0beffaa 100644
> > --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> > +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> > @@ -81,6 +81,7 @@ struct cmdq_client *cmdq_mbox_create(struct device *dev, int index, u32 timeout)
> >  	client->client.dev = dev;
> >  	client->client.tx_block = false;
> >  	client->chan = mbox_request_channel(&client->client, index);
> > +	mutex_init(&client->mutex);
> >  
> >  	if (IS_ERR(client->chan)) {
> >  		long err;
> > @@ -352,9 +353,11 @@ int cmdq_pkt_flush_async(struct cmdq_pkt *pkt, cmdq_async_flush_cb cb,
> >  		spin_unlock_irqrestore(&client->lock, flags);
> >  	}
> >  
> > +	mutex_lock(&client->mutex);
> >  	mbox_send_message(client->chan, pkt);
> >  	/* We can send next packet immediately, so just call txdone. */
> >  	mbox_client_txdone(client->chan, 0);
> > +	mutex_unlock(&client->mutex);
> >  
> >  	return 0;
> >  }
> > diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> > index a74c1d5acdf3..0f9071cd1bc7 100644
> > --- a/include/linux/soc/mediatek/mtk-cmdq.h
> > +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> > @@ -28,6 +28,7 @@ struct cmdq_client {
> >  	struct mbox_chan *chan;
> >  	struct timer_list timer;
> >  	u32 timeout_ms; /* in unit of microsecond */
> > +	struct mutex mutex;
> >  };
> >  
> >  /**
>