From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1431546-1518324283-2-13299263222358549615 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='uk', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518324282; b=GKfN0tVNdDbLNC/1O/Zl8IxHbvNCh1inLQBJBDvbkVwwDZR Ohn8IJZAbzWJTzafAjrrQPFnViMcshVyEGGpajQwoz8aZebE/Gve73cQ5he1Ku7B rSiQq61xXFxoK/lsDnvuSZZEagRzNAhzgKDcU2DdougIrh3Tr1V0mX+AqkLFafyM oX5I7QLGmCopDLTNdAsVyICfFY9vWMaui7AUKxZI621DPddv4bSAM7wOZ+NlAeRY 19B2lNT1B+oHmdU68MEkH4aV9AO8Rx4RmmOJeNFN3VMd2VgybJ1e+/+H22ndVSVC hWolBEzTYdUMfP6mL5Wz0s7S4B1D33WdithPcfw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:content-transfer-encoding :mime-version:from:to:cc:date:message-id:subject:in-reply-to :sender:list-id; s=arctest; t=1518324282; bh=eP/AH+lQxHwKuULdilv KNit5kzgkEjlU3g0pBS3v6BI=; b=iV+cRrY2q8YPGk3NoStWf4Kzob03ydHadh/ hfqLV34T1M0Kj+EX5eTdslGLaz5UkqOGAgoO7rsNPPzqa51qZWezj2eofnm+cXmS G1++r4s4FmHrXvAMbI+vlCaFN79Y6Gos6pAUENOgmHMcRDUZO7JnJm0prYmzCXBN EJEPtI/qXyTQ2a83VEdlQLFMMwOz0qB0dVuhVG3+PB947JXD4aLzcfF5W7sqnziU HgZ15lrHSkpM7jBy5GNKmawXqGYbMztcRMzJ8BMHyhvob52afEAa+hyAh4beJMXS mJ4B6rjfB9I/giTT8bfZJf6XaYayCaDLZ3Q+Van1eSZrn6Mv1Rw== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=decadent.org.uk header.result=pass header_is_org_domain=yes Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=decadent.org.uk header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753358AbeBKEnG (ORCPT ); Sat, 10 Feb 2018 23:43:06 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41892 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752871AbeBKEd7 (ORCPT ); Sat, 10 Feb 2018 23:33:59 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Alexander Potapenko" , "Eric W. Biederman" Date: Sun, 11 Feb 2018 04:31:11 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 085/136] net/sctp: Always set scope_id in sctp_inet6_skb_msgname In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.16.54-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" commit 7c8a61d9ee1df0fb4747879fa67a99614eb62fec upstream. Alexandar Potapenko while testing the kernel with KMSAN and syzkaller discovered that in some configurations sctp would leak 4 bytes of kernel stack. Working with his reproducer I discovered that those 4 bytes that are leaked is the scope id of an ipv6 address returned by recvmsg. With a little code inspection and a shrewd guess I discovered that sctp_inet6_skb_msgname only initializes the scope_id field for link local ipv6 addresses to the interface index the link local address pertains to instead of initializing the scope_id field for all ipv6 addresses. That is almost reasonable as scope_id's are meaniningful only for link local addresses. Set the scope_id in all other cases to 0 which is not a valid interface index to make it clear there is nothing useful in the scope_id field. There should be no danger of breaking userspace as the stack leak guaranteed that previously meaningless random data was being returned. Fixes: 372f525b495c ("SCTP: Resync with LKSCTP tree.") History-tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Reported-by: Alexander Potapenko Tested-by: Alexander Potapenko Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller [bwh: Backported to 3.16: - Adjust context - Add braces] Signed-off-by: Ben Hutchings --- --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -787,6 +787,8 @@ static void sctp_inet6_skb_msgname(struc if (ipv6_addr_type(&addr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL) { struct sctp_ulpevent *ev = sctp_skb2event(skb); addr->v6.sin6_scope_id = ev->iif; + } else { + addr->v6.sin6_scope_id = 0; } }