From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3759000-1519415911-2-533023181707205754 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='CN', FromHeader='org', 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=1519415911; b=MP501fuBzuIU6rFzVBhgY6VUreTcIvhgSQgipzNzYFcRto2 zYWmd9pPbDWK4goG88pWlCcieuqEwfeBCy3BMGBWoq2SIT01BHin2YbJ1CYnhD4s vHphprIK/O2po8mrVonE3ru5Ro601whSMBPrPH/+ChzOL3aKsaf+v50URg01Wv+M ZVKiJFCdSml5OPztU2k5TLmHiJGl7ykl7JDPIsZuAyhHM6EDqzbOF/rENaJaBWOq KxceDEIBE3Bf6QnNluOB2Vs/T+Rjv3qg+JYxX5AU2UJ5QmiHI+eapP4CkULykHQO rcB5tu+U7eDO4EV4GUPj7P+JCyDc226+6wYzA1Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1519415911; bh=ovxd4J9vtVnX5kQldVxMrr0dic cpDltU0JoH1IIvS4g=; b=oNYfvnc+QtEI4XA4BHCnHLvYx0qHfRXnY3MDgExKvs 8HoSp2kvrTSHOS3scIk038F5UOVEWZCIVK9W3D5orGNcDAg93zar+zMkEBQXbfcq 7AwMyNAH2h7+PEuOkQF33IoaeNxcguTW0SQ3gcEC9rJyPh3yQT+nrotu5m3XIoCc luPGrVfoWgyRhgymR9lJMZCR0OrS17CB9ggPoWCfa0kHkJ6Ov2a84D6fWX6/k0Pg 3lsRvjT9NwqH/kQ19/ylAINqAKTttXMaY1GWonMivIsWHl73wLUjf3FaOT5sJee3 Dq++DLWY1lDfVCuKeMKLK4n6DRyHMhXD6GzeBOf+ogHQ== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; 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=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; 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=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933041AbeBWSoR (ORCPT ); Fri, 23 Feb 2018 13:44:17 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:42504 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932663AbeBWSoP (ORCPT ); Fri, 23 Feb 2018 13:44:15 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+114b15f2be420a8886c3@syzkaller.appspotmail.com, Tom Herbert , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.9 002/145] kcm: Check if sk_user_data already set in kcm_attach Date: Fri, 23 Feb 2018 19:25:08 +0100 Message-Id: <20180223170724.968449379@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180223170724.669759283@linuxfoundation.org> References: <20180223170724.669759283@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tom Herbert commit e5571240236c5652f3e079b1d5866716a7ad819c upstream. This is needed to prevent sk_user_data being overwritten. The check is done under the callback lock. This should prevent a socket from being attached twice to a KCM mux. It also prevents a socket from being attached for other use cases of sk_user_data as long as the other cases set sk_user_data under the lock. Followup work is needed to unify all the use cases of sk_user_data to use the same locking. Reported-by: syzbot+114b15f2be420a8886c3@syzkaller.appspotmail.com Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module") Signed-off-by: Tom Herbert Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/kcm/kcmsock.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -1404,9 +1404,18 @@ static int kcm_attach(struct socket *soc return err; } - sock_hold(csk); - write_lock_bh(&csk->sk_callback_lock); + + /* Check if sk_user_data is aready by KCM or someone else. + * Must be done under lock to prevent race conditions. + */ + if (csk->sk_user_data) { + write_unlock_bh(&csk->sk_callback_lock); + strp_done(&psock->strp); + kmem_cache_free(kcm_psockp, psock); + return -EALREADY; + } + psock->save_data_ready = csk->sk_data_ready; psock->save_write_space = csk->sk_write_space; psock->save_state_change = csk->sk_state_change; @@ -1414,8 +1423,11 @@ static int kcm_attach(struct socket *soc csk->sk_data_ready = psock_data_ready; csk->sk_write_space = psock_write_space; csk->sk_state_change = psock_state_change; + write_unlock_bh(&csk->sk_callback_lock); + sock_hold(csk); + /* Finished initialization, now add the psock to the MUX. */ spin_lock_bh(&mux->lock); head = &mux->psocks;