From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbgHATqY (ORCPT ); Sat, 1 Aug 2020 15:46:24 -0400 From: Peilin Ye Subject: [Linux-kernel-mentees] [PATCH net] net/smc: Prevent kernel-infoleak in __smc_diag_dump() Date: Sat, 1 Aug 2020 15:44:40 -0400 Message-Id: <20200801194440.246747-1-yepeilin.cs@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Ursula Braun , Karsten Graul Cc: Peilin Ye , Hans Wippel , "David S. Miller" , Jakub Kicinski , Dan Carpenter , Arnd Bergmann , Greg Kroah-Hartman , linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-kernel@vger.kernel.org __smc_diag_dump() is potentially copying uninitialized kernel stack memory into socket buffers, since the compiler may leave a 4-byte hole near the beginning of `struct smcd_diag_dmbinfo`. Fix it by initializing `dinfo` with memset(). Cc: stable@vger.kernel.org Fixes: 4b1b7d3b30a6 ("net/smc: add SMC-D diag support") Suggested-by: Dan Carpenter Signed-off-by: Peilin Ye --- Reference: https://lwn.net/Articles/417989/ $ pahole -C "smcd_diag_dmbinfo" net/smc/smc_diag.o struct smcd_diag_dmbinfo { __u32 linkid; /* 0 4 */ /* XXX 4 bytes hole, try to pack */ __u64 peer_gid __attribute__((__aligned__(8))); /* 8 8 */ __u64 my_gid __attribute__((__aligned__(8))); /* 16 8 */ __u64 token __attribute__((__aligned__(8))); /* 24 8 */ __u64 peer_token __attribute__((__aligned__(8))); /* 32 8 */ /* size: 40, cachelines: 1, members: 5 */ /* sum members: 36, holes: 1, sum holes: 4 */ /* forced alignments: 4, forced holes: 1, sum forced holes: 4 */ /* last cacheline: 40 bytes */ } __attribute__((__aligned__(8))); $ _ net/smc/smc_diag.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/net/smc/smc_diag.c b/net/smc/smc_diag.c index e1f64f4ba236..da9ba6d1679b 100644 --- a/net/smc/smc_diag.c +++ b/net/smc/smc_diag.c @@ -170,13 +170,15 @@ static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb, (req->diag_ext & (1 << (SMC_DIAG_DMBINFO - 1))) && !list_empty(&smc->conn.lgr->list)) { struct smc_connection *conn = &smc->conn; - struct smcd_diag_dmbinfo dinfo = { - .linkid = *((u32 *)conn->lgr->id), - .peer_gid = conn->lgr->peer_gid, - .my_gid = conn->lgr->smcd->local_gid, - .token = conn->rmb_desc->token, - .peer_token = conn->peer_token - }; + struct smcd_diag_dmbinfo dinfo; + + memset(&dinfo, 0, sizeof(dinfo)); + + dinfo.linkid = *((u32 *)conn->lgr->id); + dinfo.peer_gid = conn->lgr->peer_gid; + dinfo.my_gid = conn->lgr->smcd->local_gid; + dinfo.token = conn->rmb_desc->token; + dinfo.peer_token = conn->peer_token; if (nla_put(skb, SMC_DIAG_DMBINFO, sizeof(dinfo), &dinfo) < 0) goto errout; -- 2.25.1