Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751411AbdISTP5 convert rfc822-to-8bit (ORCPT ); Tue, 19 Sep 2017 15:15:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:42486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751237AbdISTP4 (ORCPT ); Tue, 19 Sep 2017 15:15:56 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 698732133F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=robh+dt@kernel.org X-Google-Smtp-Source: AOwi7QDkmf49W0OgQofvMh2cfdG2Mwac84prrjCmvI66rPodRvnvTyho5z17qeM/NQu+f1Z5kitV6jWA9f+aYdW6BWU= MIME-Version: 1.0 In-Reply-To: <59C16197.4040403@gmail.com> References: <1505039164-25468-1-git-send-email-geert@linux-m68k.org> <59C16197.4040403@gmail.com> From: Rob Herring Date: Tue, 19 Sep 2017 14:15:33 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] of: overlay: Fix uninitialized vars in dup_and_fixup_symbol_prop() To: Frank Rowand Cc: Geert Uytterhoeven , Pantelis Antoniou , Grant Likely , Arnd Bergmann , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2052 Lines: 55 On Tue, Sep 19, 2017 at 1:27 PM, Frank Rowand wrote: > On 09/10/17 03:26, 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 >> --- >> drivers/of/overlay.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c >> index 8ecfee31ab6d3874..ebe19e0f8e4d1f4b 100644 >> --- a/drivers/of/overlay.c >> +++ b/drivers/of/overlay.c >> @@ -108,7 +108,7 @@ static struct property *dup_and_fixup_symbol_prop(struct of_overlay *ov, >> int overlay_name_len; >> int target_path_len; >> >> - if (!prop->value) >> + if (!ov->count || !prop->value) >> return NULL; >> symbol_path = prop->value; >> >> > > I did not see this patch due to an overzealous spam filter. I noticed it > when Rob replied with his applied email. > > This check is not needed to prevent accessing overlay_name_len and ovinfo > when ov->count == 0. That is already prevented by: > > if (k >= ov->count) > goto err_free; > > because k will be zero and ov->count will be zero. Okay, will drop. Rob