From owner-svn-src-all@freebsd.org Tue Oct 8 23:34:49 2019 Return-Path: Delivered-To: svn-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 3090213A64F; Tue, 8 Oct 2019 23:34:49 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 46ntx50RMWz4ffR; Tue, 8 Oct 2019 23:34:49 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id E67877CC0; Tue, 8 Oct 2019 23:34:48 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x98NYmO7058696; Tue, 8 Oct 2019 23:34:48 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x98NYmsk058695; Tue, 8 Oct 2019 23:34:48 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201910082334.x98NYmsk058695@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Tue, 8 Oct 2019 23:34:48 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r353331 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: markj X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 353331 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Oct 2019 23:34:49 -0000 Author: markj Date: Tue Oct 8 23:34:48 2019 New Revision: 353331 URL: https://svnweb.freebsd.org/changeset/base/353331 Log: Fix handling of empty SCM_RIGHTS messages. As unp_internalize() processes the input control messages, it builds an output mbuf chain containing the internalized representations of those messages. In one special case, that of an empty SCM_RIGHTS message, the message is simply discarded. However, the loop which appends mbufs to the output chain assumed that each iteration would produce an mbuf, resulting in a null pointer dereference if an empty SCM_RIGHTS message was followed by a non-empty message. Fix this by advancing the output mbuf chain tail pointer only if an internalized control message was produced. Reported by: syzbot+1b5cced0f7fad26ae382@syzkaller.appspotmail.com MFC after: 1 week Sponsored by: The FreeBSD Foundation Modified: head/sys/kern/uipc_usrreq.c Modified: head/sys/kern/uipc_usrreq.c ============================================================================== --- head/sys/kern/uipc_usrreq.c Tue Oct 8 21:40:42 2019 (r353330) +++ head/sys/kern/uipc_usrreq.c Tue Oct 8 23:34:48 2019 (r353331) @@ -2318,7 +2318,8 @@ unp_internalize(struct mbuf **controlp, struct thread goto out; } - controlp = &(*controlp)->m_next; + if (*controlp != NULL) + controlp = &(*controlp)->m_next; if (CMSG_SPACE(datalen) < clen) { clen -= CMSG_SPACE(datalen); cm = (struct cmsghdr *)