From owner-svn-src-head@freebsd.org Sat Jul 4 06:27:29 2020 Return-Path: Delivered-To: svn-src-head@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 38354363123; Sat, 4 Jul 2020 06:27:29 +0000 (UTC) (envelope-from mjg@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) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 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 49zMM46bhdz4F7r; Sat, 4 Jul 2020 06:27:28 +0000 (UTC) (envelope-from mjg@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 C1A4518320; Sat, 4 Jul 2020 06:27:28 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 0646RSgL026834; Sat, 4 Jul 2020 06:27:28 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 0646RSEi026833; Sat, 4 Jul 2020 06:27:28 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <202007040627.0646RSEi026833@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Sat, 4 Jul 2020 06:27:28 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r362923 - head/sys/fs/devfs X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/fs/devfs X-SVN-Commit-Revision: 362923 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Jul 2020 06:27:29 -0000 Author: mjg Date: Sat Jul 4 06:27:28 2020 New Revision: 362923 URL: https://svnweb.freebsd.org/changeset/base/362923 Log: devfs: fix a vnode use-after-free in devfs_ioctl The vnode to be replaced was read with a shared lock, meaning 2 racing threads can find the same one. While here clean it up a little bit. Modified: head/sys/fs/devfs/devfs_vnops.c Modified: head/sys/fs/devfs/devfs_vnops.c ============================================================================== --- head/sys/fs/devfs/devfs_vnops.c Sat Jul 4 06:25:41 2020 (r362922) +++ head/sys/fs/devfs/devfs_vnops.c Sat Jul 4 06:27:28 2020 (r362923) @@ -787,6 +787,7 @@ devfs_ioctl(struct vop_ioctl_args *ap) struct vnode *vpold, *vp; struct cdevsw *dsw; struct thread *td; + struct session *sess; struct cdev *dev; int error, ref, i; const char *p; @@ -836,18 +837,18 @@ devfs_ioctl(struct vop_ioctl_args *ap) * nothing left to do. */ sx_slock(&proctree_lock); - if (td->td_proc->p_session->s_ttyvp == vp || - td->td_proc->p_session->s_ttyp == NULL) { + sess = td->td_proc->p_session; + if (sess->s_ttyvp == vp || sess->s_ttyp == NULL) { sx_sunlock(&proctree_lock); return (0); } - vpold = td->td_proc->p_session->s_ttyvp; - VREF(vp); - SESS_LOCK(td->td_proc->p_session); - td->td_proc->p_session->s_ttyvp = vp; - td->td_proc->p_session->s_ttydp = cdev2priv(dev); - SESS_UNLOCK(td->td_proc->p_session); + vrefact(vp); + SESS_LOCK(sess); + vpold = sess->s_ttyvp; + sess->s_ttyvp = vp; + sess->s_ttydp = cdev2priv(dev); + SESS_UNLOCK(sess); sx_sunlock(&proctree_lock);