linux-kernel - Re: [PATCH] OMAP: DSS2: OMAPFB: fix potential GPF

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Message-ID: <20210627114816.5e9d042b@gmail.com>
Date:   Sun, 27 Jun 2021 11:48:16 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Aaro Koskinen <aaro.koskinen@....fi>
Cc:     gustavoars@...nel.org, sam@...nborg.org, tomi.valkeinen@...com,
        linux-omap@...r.kernel.org, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH] OMAP: DSS2: OMAPFB: fix potential GPF

On Sun, 27 Jun 2021 02:14:23 +0300
Aaro Koskinen <aaro.koskinen@....fi> wrote:

> Hi,
> 
> On Sat, Jun 26, 2021 at 01:33:23AM +0300, Pavel Skripkin wrote:
> > In case of allocation failures, all code paths was jumping
> > to this code:
> > 
> > err:
> > 	kfree(fbi);
> > 	kfree(var);
> > 	kfree(fbops);
> > 
> > 	return r;
> > 
> > Since all 3 pointers placed on stack and don't initialized, they
> > will be filled with some random values, which leads to
> > deferencing random pointers in kfree(). Fix it by rewriting
> > error handling path.
> 
> They are initialized before the first goto:
> 
> [...]
> 	fbi = NULL;
> 	var = NULL;
> 	fbops = NULL;
> 
> 	fbi = kzalloc(sizeof(*fbi), GFP_KERNEL);
> 	if (fbi == NULL) {
> 		r = -ENOMEM;
> 		goto err;
> 	}
> [...]
> 

Hi! 

Im sorry for this, I should not stay to late night reviewing the code
next time :(




With regards,
Pavel Skripkin