From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Fri, 17 Apr 2026 11:48:06 +0200 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 1wDfny-00D9AG-0e for lore@lore.pengutronix.de; Fri, 17 Apr 2026 11:48:06 +0200 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 1wDfnx-00076k-Ki for lore@pengutronix.de; Fri, 17 Apr 2026 11:48:06 +0200 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=fsG2H5LvlFpxjfoFuY9qirK1IeCFkqGmCtYwSS1aREk=; b=BVv08EGnJ626GNvtxb447+09+X wXV8XBm1kGks6C1Bxnom/7Ctem4nGH+8J/hZpFikmJBCOG/xrK1II4hmK7RrAYnc+A8prc2xHnrBt gUMsJUEXyv5NgPbct420QwgkmH5q0USf/TwvwRoKKOzSTU+3DeS8sab4MSXCeg7XTEguu3uVmFSMc 7hHDmAVffjGkaQAd4AmVOlXHiLDNIT278rVDGe3lifhOxbDDZYOOYaOTLEiFKSzACyQryBlSyReN+ gNADLhh58BhGjucBLsCbkpGidmJU8ShbzChCBJ50MK/Trc71RUURcVjTgGizCDx2sNWqbZicrQ+zL ylqVgF4Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wDfnb-00000003r1K-3Zax; Fri, 17 Apr 2026 09:47:43 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wDfnZ-00000003r0t-2YKL for barebox@lists.infradead.org; Fri, 17 Apr 2026 09:47:42 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1wDfnY-0006x1-1M; Fri, 17 Apr 2026 11:47:40 +0200 Message-ID: <4d2eec0f-4527-4e9d-8bad-62e275a7df17@pengutronix.de> Date: Fri, 17 Apr 2026 11:47:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Sascha Hauer , BAREBOX Cc: "Claude Opus 4.6 (1M context)" References: <20260402-net-dhcp-buffer-overflows-v2-0-fe4ca7c4b718@pengutronix.de> <20260402-net-dhcp-buffer-overflows-v2-2-fe4ca7c4b718@pengutronix.de> From: Ahmad Fatoum Content-Language: en-US, de-DE, de-BE In-Reply-To: <20260402-net-dhcp-buffer-overflows-v2-2-fe4ca7c4b718@pengutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260417_024741_684510_415C836E X-CRM114-Status: GOOD ( 18.86 ) 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=-5.2 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 2/3] net: dhcp: use xstrndup for bp_file to prevent read past field 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) On 4/2/26 8:59 AM, Sascha Hauer wrote: > bootp_copy_net_params() uses strlen() and xstrdup() on bp->bp_file, > which is a fixed 128-byte field in the BOOTP packet. If a DHCP server > sends a packet where all 128 bytes are non-null, strlen() reads past > the field boundary into the options data looking for a null terminator, > and xstrdup() then copies the oversized result. > > Use a simple bp->bp_file[0] check for the non-empty test and > xstrndup() bounded by sizeof(bp->bp_file) to ensure we never read > past the field. > > Signed-off-by: Sascha Hauer > Co-Authored-By: Claude Opus 4.6 (1M context) Reviewed-by: Ahmad Fatoum > --- > net/dhcp.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/dhcp.c b/net/dhcp.c > index 1cb3fef5d7..f4e4033351 100644 > --- a/net/dhcp.c > +++ b/net/dhcp.c > @@ -158,8 +158,8 @@ static void bootp_copy_net_params(struct bootp *bp) > dhcp_result->ip = net_read_ip(&bp->bp_yiaddr); > dhcp_result->serverip = net_read_ip(&bp->bp_siaddr); > > - if (strlen(bp->bp_file) > 0) > - dhcp_result->bootfile = xstrdup(bp->bp_file); > + if (bp->bp_file[0] != '\0') > + dhcp_result->bootfile = xstrndup(bp->bp_file, sizeof(bp->bp_file)); > } > > static int dhcp_set_string_options(int option, const char *str, u8 *e) > -- 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 |