linux-kernel - Re: [PATCH][V2] RDMA/nes: do not leak uninitialized resp.reserved to userspace Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit

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Date:   Tue, 5 Sep 2017 09:40:41 -0500
From:   Chien Tin Tung <chien.tin.tung@...el.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Faisal Latif <faisal.latif@...el.com>,
        Doug Ledford <dledford@...hat.com>,
        Sean Hefty <sean.hefty@...el.com>,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        linux-rdma@...r.kernel.org, kernel-janitors@...r.kernel.org,
        stable@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][V2] RDMA/nes: do not leak uninitialized resp.reserved to
 userspace Content-Type: text/plain; charset="utf-8"
 Content-Transfer-Encoding: 8bit

On Mon, Sep 04, 2017 at 02:37:05PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> resp.reserved has not been initialized and so the copy_to_user (via
> ib_copy_to_udata) is copying uninitialized data from the stack back
> to user space which is a potential information leak. Fix this by
> initializing all of resp to zero.

Reserved field is not copied as the length of reserved is subtracted
from the size of resp and passed to ib_copy_to_udata.

 if (ib_copy_to_udata(udata, &resp, sizeof resp - sizeof resp.reserved)) {


This patch is not necessary.

Chien