linux-kernel - Re: [PATCH v2] cxgb4: do not dma memory off of the stack

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Message-ID: <20191004181648.GA28069@ziepe.ca>
Date:   Fri, 4 Oct 2019 15:16:48 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Potnuri Bharat Teja <bharat@...lsio.com>,
        Doug Ledford <dledford@...hat.com>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org, Nicolas Waisman <nico@...mle.com>
Subject: Re: [PATCH v2] cxgb4: do not dma memory off of the stack

On Tue, Oct 01, 2019 at 06:56:11PM +0200, Greg KH wrote:
> Nicolas pointed out that the cxgb4 driver is doing dma off of the stack,
> which is generally considered a very bad thing.  On some architectures
> it could be a security problem, but odds are none of them actually run
> this driver, so it's just a "normal" bug.
> 
> Resolve this by allocating the memory for a message off of the heap
> instead of the stack.  kmalloc() always will give us a proper memory
> location that DMA will work correctly from.
> 
> Reported-by: Nicolas Waisman <nico@...mle.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Applied to for-rc, thanks

Jason