From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Wed, 13 Nov 2024 18:46:52 +0100 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1tBHS8-001WLB-1R for lore@lore.pengutronix.de; Wed, 13 Nov 2024 18:46:52 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1tBHS7-0004Yz-Np for lore@pengutronix.de; Wed, 13 Nov 2024 18:46:52 +0100 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tUi5AAeTWnaLNnwoiMZRJNubQ2jvoaTfvJM16gpx9es=; b=jUrUF3fhyQvlJH2ppUQk+20gB+ kCplwDmWl8pHzeO9ZW1Hj5ebNL1rkETr8QY4d/vwX4p/ME7gi+tFfoZIT+qNLAbn+FWpqENOCvh0c 0B/4Ti32NwHsu7nt2yco7PBCqb48eaDFIAGUe5CStJ/aCvfRpm+TDRi95fUadbRCdmo2BdCy1B695 wL2QyP2smBYD9a6rkP62sO+aLkWMkKaWoBA2rPW/QKnYj4pzxD6i4VI/sX6ZU0D3NY2Dpn7U+zmFU yYgBjWNtABcEwe62XI31gEtsZ0/8kWxHPOvtxxrvh5wn/k6gzHCB+r2TzECHea0/z9LeSwSBncQMq ZvEcx2RA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tBHRU-00000007bPG-1tGv; Wed, 13 Nov 2024 17:46:12 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tBHRR-00000007bON-01nY for barebox@lists.infradead.org; Wed, 13 Nov 2024 17:46:10 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[IPV6:::1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1tBHRM-0004LY-QP; Wed, 13 Nov 2024 18:46:04 +0100 Message-ID: Date: Wed, 13 Nov 2024 18:46:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: AbdelRahman Yossef , Sascha Hauer Cc: barebox@lists.infradead.org References: <20241112191058.397165-1-abdelrahmanyossef12@gmail.com> <383d6b94-1152-4257-b18c-9f31857944ca@pengutronix.de> Content-Language: en-US From: Ahmad Fatoum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241113_094609_069980_76042E11 X-CRM114-Status: GOOD ( 26.43 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.3 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH v2] of: fdt: fix possible overflow during parsing of fdt X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) Hi, On 13.11.24 13:37, AbdelRahman Yossef wrote: > I will update the patch and send it as v4. > > Is it enough to just add the changes to Changelog or change the commit message? The old commit message wouldn't reflect the new changes, so please rewrite it to be in-line with the diff. The changelog is separate and should look like this or similar: --- v3 -> v4: - replace < 0 with <= 0 (Sascha) - remove + 1 in strnlen (Sascha) v2 -> v3: - did foo to bar ($name_of_person_who_suggested_it) v1 > v2: - did baz to bazzer --- Thanks, Ahmad > > On Wed, Nov 13, 2024 at 2:17 PM Sascha Hauer wrote: >> >> On Tue, Nov 12, 2024 at 08:56:58PM +0100, Ahmad Fatoum wrote: >>> Hello Abdelrahman, >>> >>> Thanks for your patch. >>> >>> On 12.11.24 20:10, Abdelrahman Youssef wrote: >>>> While fuzzing, the name marked by FDT_BEGIN_NODE sometimes extends beyond >>>> the struct block area, Causing a heap-overflow. >>>> >>>> Since `maxlen` is an unsigned integer representing the length of name, >>>> It can be negative, So it overflows to large numbers, Causing strnlen() >>>> to overflow. >>>> >>>> So we can just change the type of maxlen to signed and check if it's negative. >>>> >>>> Signed-off-by: Abdelrahman Youssef >>>> --- >>> >>> Changelog would've been nice. This also should have been v3 not v2. >>> >>>> drivers/of/fdt.c | 7 ++++++- >>>> 1 file changed, 6 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c >>>> index 2c3ea31394..d8d8a4922c 100644 >>>> --- a/drivers/of/fdt.c >>>> +++ b/drivers/of/fdt.c >>>> @@ -176,7 +176,7 @@ static struct device_node *__of_unflatten_dtb(const void *infdt, int size, >>>> void *dt_strings; >>>> struct fdt_header f; >>>> int ret; >>>> - unsigned int maxlen; >>>> + int maxlen; >>>> const struct fdt_header *fdt = infdt; >>>> >>>> ret = fdt_parse_header(infdt, size, &f); >>>> @@ -210,6 +210,11 @@ static struct device_node *__of_unflatten_dtb(const void *infdt, int size, >>>> maxlen = (unsigned long)fdt + f.off_dt_struct + >>>> f.size_dt_struct - (unsigned long)name; >>>> >>>> + if (maxlen < 0) { >>>> + ret = -ESPIPE; >>>> + goto err; >>>> + } >>>> + >>>> len = strnlen(name, maxlen + 1); >>> >>> Hmm is this + 1 correct? I am wondering if we should be dropping >>> the + 1 here and make it maxlen <= 0 above. >> >> I think maxlen <= 0 is correct indepent of what follows next, because >> maxlen is the length of a string and a valid string has a minimal length >> of one byte ('\0'). >> >> Next we shouldn't look at bytes exceeding maxlen, so indeed >> strnlen(name, maxlen) should be correct. When changing this we have >> to adjust the following if (len > maxlen) check to >=. >> >> Sascha >> >> -- >> Pengutronix e.K. | | >> Steuerwalder Str. 21 | http://www.pengutronix.de/ | >> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | >> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |