linux-kernel - Re: [PATCH] of: overlay: Fix uninitialized vars in dup_and_fixup_symbol

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Message-ID: <20170919172756.3fsud4g4grracxqt@rob-hp-laptop>
Date:   Tue, 19 Sep 2017 12:27:56 -0500
From:   Rob Herring <robh@...nel.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Frank Rowand <frowand.list@...il.com>,
        Grant Likely <grant.likely@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] of: overlay: Fix uninitialized vars in
 dup_and_fixup_symbol_prop()

On Sun, Sep 10, 2017 at 12:26:04PM +0200, Geert Uytterhoeven wrote:
> With gcc 4.1.2:
> 
>     drivers/of/overlay.c: In function ‘dup_and_fixup_symbol_prop’:
>     drivers/of/overlay.c:108: warning: ‘overlay_name_len’ may be used uninitialized in this function
>     drivers/of/overlay.c:100: warning: ‘ovinfo’ may be used uninitialized in this function
> 
> Indeed, if ov->count == 0, both variables are uninitialized, which may
> lead to a crash when dereferencing ovinfo later.
> 
> Currently this is a false positive, as the sole creator of of_overlay
> structures (of_build_overlay_info(), introduced in commit
> 7518b5890d8ac366 ("of/overlay: Introduce DT overlay support") checks for
> this.
> 
> To prevent future issues, add a check for a zero ov->count to
> dup_and_fixup_symbol_prop().  Note that this does not get rid of the
> actual compiler warning.
> 
> Fixes: d1651b03c2df75db ("of: overlay: add overlay symbols to live device tree")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
>  drivers/of/overlay.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied.

Rob