From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Fri, 17 Apr 2026 11:29:05 +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 1wDfVZ-00D8qF-25 for lore@lore.pengutronix.de; Fri, 17 Apr 2026 11:29:05 +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 1wDfVZ-0000kJ-2k for lore@pengutronix.de; Fri, 17 Apr 2026 11:29:05 +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=mpbZtQDQcs8O/VOD1uR/SrSEp17zCQJRQ3GC79pC0cU=; b=1lM8DULYfX7h81/ldZjhhGQESL lLHJMrz8AHFCAb2d7PvqFLsXHb0f5YFEfI/myt6cJZryhbfF9EDsoIA/9BUPk5hVnMRRaSvjrexbW CFrwjsxsXCsudcSSLpQneoxJjU5qx+ys0aVgxOtBlPJR6sGtifdemjdhTBY8ZcxF8qxhKoYX/86gX r9pWITQOCZT46i0bpdX3RKJL++UV74Zr8P1CfVY1ohmiKRcYovPkK+v/peCA4B9V9z+i7zcf7U09t uqTOSIPQH+7VnOyFuDgy4TbbMpnuy0dGFbVPhxA9n34vn4TdUoQ8j5Hpb774jFFTypKw5vQnsPt4Q XqJOzB4Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wDfVA-00000003ot2-3j75; Fri, 17 Apr 2026 09:28:40 +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 1wDfUh-00000003oAt-1fqb for barebox@lists.infradead.org; Fri, 17 Apr 2026 09:28:15 +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 1wDfUf-0000Nl-8y; Fri, 17 Apr 2026 11:28:09 +0200 Message-ID: <92b29190-41a5-4cbf-9ec8-2bdc1fe5ea81@pengutronix.de> Date: Fri, 17 Apr 2026 11:28:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Sascha Hauer , BAREBOX Cc: "Claude Opus 4.6 (1M context)" References: <20260402-net-tftp-buffer-overflows-v1-0-0a18aa8ea19e@pengutronix.de> <20260402-net-tftp-buffer-overflows-v1-2-0a18aa8ea19e@pengutronix.de> Content-Language: en-US, de-DE, de-BE From: Ahmad Fatoum In-Reply-To: <20260402-net-tftp-buffer-overflows-v1-2-0a18aa8ea19e@pengutronix.de> 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-20260417_022811_863893_B780E4F2 X-CRM114-Status: GOOD ( 20.59 ) 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 2/4] fs: tftp: fix OACK option parsing bounds check 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 9:21 AM, Sascha Hauer wrote: > The bounds check in tftp_parse_oack() uses 'val > s + len' to detect > when the value pointer exceeds the packet. Since 's' advances through > the buffer while 'len' stays constant, 's + len' always points past > 'pkt + len', making the check always false — it is dead code. > > The forced null at pkt[len - 1] provides partial protection, but when > the last option key ends exactly at pkt[len - 1], val equals pkt + len > and the subsequent strlen(val) reads past the packet boundary into > uninitialized packet buffer data. > > Fix by checking 'val >= pkt + len' instead, which correctly bounds val > against the actual end of the packet data. Using >= because when val > equals pkt + len there is no room for a value string. > > Signed-off-by: Sascha Hauer > Co-Authored-By: Claude Opus 4.6 (1M context) Reviewed-by: Ahmad Fatoum > --- > fs/tftp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/tftp.c b/fs/tftp.c > index 1b15bc18e7..03e9d552aa 100644 > --- a/fs/tftp.c > +++ b/fs/tftp.c > @@ -370,7 +370,7 @@ static int tftp_parse_oack(struct file_priv *priv, unsigned char *pkt, int len) > while (s < pkt + len) { > opt = s; > val = s + strlen(s) + 1; > - if (val > s + len) > + if (val >= pkt + len) > break; > if (!strcmp(opt, "tsize")) > priv->filesize = simple_strtoull(val, NULL, 10); > -- 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 |