linux-kernel - Re: [PATCH 1/1] uio: Fix uio

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Message-ID: <20170613140146.GA29175@kroah.com>
Date:   Tue, 13 Jun 2017 16:01:46 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Mike Christie <mchristi@...hat.com>
Cc:     manish.rangankar@...ium.com, target-devel@...r.kernel.org,
        nab@...ux-iscsi.org, kys@...rosoft.com, haiyangz@...rosoft.com,
        sthemmin@...rosoft.com, mst@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] uio: Fix uio_device memory leak

On Wed, Jun 07, 2017 at 03:06:44PM -0500, Mike Christie wrote:
> It looks like there might be 2 issues with the uio_device allocation, or it
> looks like we are leaking the device for possibly a specific type of device
> case that I could not find but one of you may know about.
> 
> Issues:
> 1. We use devm_kzalloc to allocate the uio_device, but the release
> function, devm_kmalloc_release, is just a noop, so the memory is never freed.

What do you mean by this?  If the release function is a noop, lots of
memory in the kernel is leaking.  UIO shouldn't have to do anything
special here, is the devm api somehow broken?

If so, let's fix that, not paper over all other driver bugs by moving
the UIO code away from it :)

thanks,

greg k-h