From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ursula Braun Subject: [patch 6/9] [PATCH] ctcm: avoid wraparound in length of incoming data Date: Tue, 24 Mar 2009 14:27:48 +0100 Message-ID: <20090324133049.499414000@linux.vnet.ibm.com> References: <20090324132742.300929000@linux.vnet.ibm.com> Cc: schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, Roel Kluin , Ursula Braun To: davem@davemloft.net, netdev@vger.kernel.org, linux-s390@vger.kernel.org Return-path: Received: from mtagate4.de.ibm.com ([195.212.29.153]:49762 "EHLO mtagate4.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758582AbZCXNax (ORCPT ); Tue, 24 Mar 2009 09:30:53 -0400 Content-Disposition: inline; filename=625-ctcm-wraparound.diff Sender: netdev-owner@vger.kernel.org List-ID: From: Roel Kluin Since the receive code should tolerate any incoming garbage, it should be protected against a potential wraparound when manipulating length values within incoming data. block_len is unsigned, so a too large subtraction will cause a wraparound. Signed-off-by: Roel Kluin Signed-off-by: Ursula Braun --- drivers/s390/net/ctcm_fsms.c | 5 ++--- drivers/s390/net/ctcm_main.c | 3 ++- 2 files changed, 4 insertions(+), 4 deletions(-) diff -urpN linux-2.6/drivers/s390/net/ctcm_fsms.c linux-2.6-patched/drivers/s390/net/ctcm_fsms.c --- linux-2.6/drivers/s390/net/ctcm_fsms.c 2009-03-19 11:15:52.000000000 +0100 +++ linux-2.6-patched/drivers/s390/net/ctcm_fsms.c 2009-03-19 11:16:39.000000000 +0100 @@ -410,9 +410,8 @@ static void chx_rx(fsm_instance *fi, int priv->stats.rx_length_errors++; goto again; } - block_len -= 2; - if (block_len > 0) { - *((__u16 *)skb->data) = block_len; + if (block_len > 2) { + *((__u16 *)skb->data) = block_len - 2; ctcm_unpack_skb(ch, skb); } again: diff -urpN linux-2.6/drivers/s390/net/ctcm_main.c linux-2.6-patched/drivers/s390/net/ctcm_main.c --- linux-2.6/drivers/s390/net/ctcm_main.c 2009-03-19 11:16:39.000000000 +0100 +++ linux-2.6-patched/drivers/s390/net/ctcm_main.c 2009-03-19 11:16:39.000000000 +0100 @@ -105,7 +105,8 @@ void ctcm_unpack_skb(struct channel *ch, return; } pskb->protocol = ntohs(header->type); - if (header->length <= LL_HEADER_LENGTH) { + if ((header->length <= LL_HEADER_LENGTH) || + (len <= LL_HEADER_LENGTH)) { if (!(ch->logflags & LOG_FLAG_ILLEGALSIZE)) { CTCM_DBF_TEXT_(ERROR, CTC_DBF_ERROR, "%s(%s): Illegal packet size %d(%d,%d)"