From owner-svn-src-head@freebsd.org Fri May 15 12:47:39 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 D73E52F4B02; Fri, 15 May 2020 12:47:39 +0000 (UTC) (envelope-from hselasky@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 49Np8q5LdPz3J6W; Fri, 15 May 2020 12:47:39 +0000 (UTC) (envelope-from hselasky@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 AE725246A8; Fri, 15 May 2020 12:47:39 +0000 (UTC) (envelope-from hselasky@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 04FCldRs079422; Fri, 15 May 2020 12:47:39 GMT (envelope-from hselasky@FreeBSD.org) Received: (from hselasky@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 04FCldp6079421; Fri, 15 May 2020 12:47:39 GMT (envelope-from hselasky@FreeBSD.org) Message-Id: <202005151247.04FCldp6079421@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: hselasky set sender to hselasky@FreeBSD.org using -f From: Hans Petter Selasky Date: Fri, 15 May 2020 12:47:39 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r361075 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: hselasky X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 361075 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: Fri, 15 May 2020 12:47:39 -0000 Author: hselasky Date: Fri May 15 12:47:39 2020 New Revision: 361075 URL: https://svnweb.freebsd.org/changeset/base/361075 Log: Assign process group of the TTY under the "proctree_lock". This fixes a race where concurrent calls to doenterpgrp() and leavepgrp() while TIOCSCTTY is executing may result in tp->t_pgrp changing value so that tty_rel_pgrp() misses clearing it to NULL. For more details refer to the use of pgdelete() in the kernel. No functional change intended. Panic backtrace: __mtx_lock_sleep() # page fault due to using destroyed mutex tty_signal_pgrp() tty_ioctl() ptsdev_ioctl() kern_ioctl() sys_ioctl() amd64_syscall() MFC after: 1 week Sponsored by: Mellanox Technologies Modified: head/sys/kern/tty.c Modified: head/sys/kern/tty.c ============================================================================== --- head/sys/kern/tty.c Fri May 15 12:04:39 2020 (r361074) +++ head/sys/kern/tty.c Fri May 15 12:47:39 2020 (r361075) @@ -1818,7 +1818,6 @@ tty_generic_ioctl(struct tty *tp, u_long cmd, void *da tp->t_session = p->p_session; tp->t_session->s_ttyp = tp; tp->t_sessioncnt++; - sx_xunlock(&proctree_lock); /* Assign foreground process group. */ tp->t_pgrp = p->p_pgrp; @@ -1826,6 +1825,7 @@ tty_generic_ioctl(struct tty *tp, u_long cmd, void *da p->p_flag |= P_CONTROLT; PROC_UNLOCK(p); + sx_xunlock(&proctree_lock); return (0); } case TIOCSPGRP: {