From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Lacage Subject: PATCH: uninitialized memory access in tcp_parse_options Date: Mon, 21 Jun 2010 15:34:09 +0200 Message-ID: <1277127249.9469.53.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=-woEUGfWk49wmJMHdz7Ig" To: netdev@vger.kernel.org Return-path: Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:5229 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932275Ab0FUNn5 (ORCPT ); Mon, 21 Jun 2010 09:43:57 -0400 Sender: netdev-owner@vger.kernel.org List-ID: --=-woEUGfWk49wmJMHdz7Ig Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit valgrind reports the following error: ==15996== Conditional jump or move depends on uninitialised value(s) ==15996== at 0x6E63E4C: tcp_parse_options (tcp_input.c:3776) ==15996== by 0x6E856A3: tcp_check_req (tcp_minisocks.c:532) ==15996== by 0x6E7F0C6: tcp_v4_hnd_req (tcp_ipv4.c:1492) ==15996== by 0x6E7F55A: tcp_v4_do_rcv (tcp_ipv4.c:1571) ==15996== by 0x6E808C5: tcp_v4_rcv (tcp_ipv4.c:1690) ==15996== by 0x6E2DA7B: ip_local_deliver_finish (ip_input.c:231) ==15996== by 0x6E2DE0C: ip_local_deliver (netfilter.h:206) ==15996== by 0x6E2E940: ip_rcv_finish (dst.h:255) ==15996== by 0x6E2F17C: ip_rcv (netfilter.h:206) ==15996== by 0x6D53D0E: __netif_receive_skb (dev.c:2873) ==15996== by 0x6D5521F: process_backlog (dev.c:3305) ==15996== by 0x6D55A20: net_rx_action (dev.c:3435) The attached patch (generated against net-next-2.6) fixes that error by making sure that user_mss is correctly initialized at the start of tcp_parse_options, just like saw_tstamp is initialized at the start of this function. To try to be coherent, this patch also removes the redundant initialization of saw_tstamp from the caller, tcp_check_req. hope this helps, Mathieu -- Mathieu Lacage Tel: +33 4 9238 5056 --=-woEUGfWk49wmJMHdz7Ig Content-Disposition: attachment; filename="tcp-options.patch" Content-Type: text/x-patch; name="tcp-options.patch"; charset="UTF-8" Content-Transfer-Encoding: 7bit diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ae3ec15..8b713ab 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3751,6 +3751,7 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx, ptr = (unsigned char *)(th + 1); opt_rx->saw_tstamp = 0; + opt_rx->user_mss = 0; while (length > 0) { int opcode = *ptr++; diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 794c2e1..21e47e7 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -527,7 +527,6 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, __be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK); int paws_reject = 0; - tmp_opt.saw_tstamp = 0; if (th->doff > (sizeof(struct tcphdr)>>2)) { tcp_parse_options(skb, &tmp_opt, &hash_location, 0); --=-woEUGfWk49wmJMHdz7Ig--