Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <9725f86f-eabe-6aaf-0ef1-74138d895834@linux.ibm.com>
Date:   Wed, 23 Feb 2022 18:59:10 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.6.0
Subject: Re: [PATCH] net/smc: Use a mutex for locking "struct smc_pnettable"
Content-Language: en-US
To:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, linux-s390@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Tony Lu <tonylu@linux.alibaba.com>
Cc:     syzbot+4f322a6d84e991c38775@syzkaller.appspotmail.com
References: <20220223100252.22562-1-fmdefrancesco@gmail.com>
From:   Karsten Graul <kgraul@linux.ibm.com>
Organization: IBM Deutschland Research & Development GmbH
In-Reply-To: <20220223100252.22562-1-fmdefrancesco@gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 23/02/2022 11:02, Fabio M. De Francesco wrote:
> smc_pnetid_by_table_ib() uses read_lock() and then it calls smc_pnet_apply_ib()
> which, in turn, calls mutex_lock(&smc_ib_devices.mutex).
> 
> read_lock() disables preemption. Therefore, the code acquires a mutex while in
> atomic context and it leads to a SAC bug.
> 
> Fix this bug by replacing the rwlock with a mutex.
> 
> Reported-and-tested-by: syzbot+4f322a6d84e991c38775@syzkaller.appspotmail.com
> Fixes: 64e28b52c7a6 ("net/smc: add pnet table namespace support")
> Confirmed-by: Tony Lu <tonylu@linux.alibaba.com>
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> ---

Thank you Fabio!

This should go to the net tree...

Acked-by: Karsten Graul <kgraul@linux.ibm.com>