linux-kernel - Re: [PATCH][next] io_uring: ensure variable ret is initialized to zero

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Message-ID: <20190926113329.GE27389@kadam>
Date:   Thu, 26 Sep 2019 14:33:29 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Colin King <colin.king@...onical.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] io_uring: ensure variable ret is initialized to
 zero

On Thu, Sep 26, 2019 at 11:56:30AM +0200, Jens Axboe wrote:
> On 9/26/19 11:50 AM, Colin King wrote:
> > From: Colin Ian King <colin.king@...onical.com>
> > 
> > In the case where sig is NULL the error variable ret is not initialized
> > and may contain a garbage value on the final checks to see if ret is
> > -ERESTARTSYS.  Best to initialize ret to zero before the do loop to
> > ensure the ret does not accidentially contain -ERESTARTSYS before the
> > loop.
> 
> Oops, weird it didn't complain. I've folded in this fix, as that commit
> isn't upstream yet. Thanks!

There is a bug in GCC where at certain optimization levels, instead of
complaining, it initializes it to zero.

regards,
dan carpenter