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From:   David Howells <dhowells@redhat.com>
In-Reply-To: <20181226135618.12784-1-baijiaju1990@gmail.com>
References: <20181226135618.12784-1-baijiaju1990@gmail.com>
To:     Jia-Ju Bai <baijiaju1990@gmail.com>
Cc:     dhowells@redhat.com, benh@kernel.crashing.org, joel@jms.id.au,
        eajames@linux.vnet.ibm.com, andrew@aj.id.au,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fsi:fsi-sbefifo: Fix possible concurrency use-after-free bugs in sbefifo_user_release
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Content-ID: <26863.1546421693.1@warthog.procyon.org.uk>
Date:   Wed, 02 Jan 2019 09:34:53 +0000
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Jia-Ju Bai <baijiaju1990@gmail.com> wrote:

> +	mutex_lock(&user->file_lock);
>  	sbefifo_release_command(user);
>  	free_page((unsigned long)user->cmd_page);
> +	mutex_unlock(&user->file_lock);

It shouldn't be necessary to do the free_page() call inside the locked
section.

David