From owner-svn-src-all@freebsd.org Sat Jun 29 16:05:53 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 6FF3D15DF7BA; Sat, 29 Jun 2019 16:05:53 +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 11F1F82A8C; Sat, 29 Jun 2019 16:05:53 +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 DC1A618A5A; Sat, 29 Jun 2019 16:05:52 +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 x5TG5qDh019556; Sat, 29 Jun 2019 16:05:52 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x5TG5qBA019555; Sat, 29 Jun 2019 16:05:52 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201906291605.x5TG5qBA019555@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Sat, 29 Jun 2019 16:05:52 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r349546 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: markj X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 349546 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 11F1F82A8C X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.96 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.999,0]; NEURAL_HAM_SHORT(-0.96)[-0.965,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] 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: Sat, 29 Jun 2019 16:05:53 -0000 Author: markj Date: Sat Jun 29 16:05:52 2019 New Revision: 349546 URL: https://svnweb.freebsd.org/changeset/base/349546 Log: Fix mutual exclusion in pipe_direct_write(). We use PIPE_DIRECTW as a semaphore for direct writes to a pipe, where the reader copies data directly from pages mapped into the writer. However, when a reader finishes such a copy, it previously cleared PIPE_DIRECTW, allowing multiple writers to race and corrupt the state used to track wired pages belonging to the writer. Fix this by having the writer clear PIPE_DIRECTW and instead use the count of unread bytes to determine whether a write is finished. Reported by: syzbot+21811cc0a89b2a87a9e7@syzkaller.appspotmail.com Reviewed by: kib, mjg Tested by: pho MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D20784 Modified: head/sys/kern/sys_pipe.c Modified: head/sys/kern/sys_pipe.c ============================================================================== --- head/sys/kern/sys_pipe.c Sat Jun 29 15:28:36 2019 (r349545) +++ head/sys/kern/sys_pipe.c Sat Jun 29 16:05:52 2019 (r349546) @@ -724,7 +724,7 @@ pipe_read(struct file *fp, struct uio *uio, struct ucr rpipe->pipe_map.pos += size; rpipe->pipe_map.cnt -= size; if (rpipe->pipe_map.cnt == 0) { - rpipe->pipe_state &= ~(PIPE_DIRECTW|PIPE_WANTW); + rpipe->pipe_state &= ~PIPE_WANTW; wakeup(rpipe); } #endif @@ -855,13 +855,17 @@ pipe_build_write_buffer(struct pipe *wpipe, struct uio } /* - * unmap and unwire the process buffer + * Unwire the process buffer. */ static void pipe_destroy_write_buffer(struct pipe *wpipe) { PIPE_LOCK_ASSERT(wpipe, MA_OWNED); + KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, + ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); + + wpipe->pipe_state &= ~PIPE_DIRECTW; vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages); wpipe->pipe_map.npages = 0; } @@ -880,13 +884,15 @@ pipe_clone_write_buffer(struct pipe *wpipe) int pos; PIPE_LOCK_ASSERT(wpipe, MA_OWNED); + KASSERT((wpipe->pipe_state & PIPE_DIRECTW) != 0, + ("%s: PIPE_DIRECTW not set on %p", __func__, wpipe)); + size = wpipe->pipe_map.cnt; pos = wpipe->pipe_map.pos; wpipe->pipe_buffer.in = size; wpipe->pipe_buffer.out = 0; wpipe->pipe_buffer.cnt = size; - wpipe->pipe_state &= ~PIPE_DIRECTW; PIPE_UNLOCK(wpipe); iov.iov_base = wpipe->pipe_buffer.buffer; @@ -925,7 +931,7 @@ retry: pipeunlock(wpipe); goto error1; } - while (wpipe->pipe_state & PIPE_DIRECTW) { + if (wpipe->pipe_state & PIPE_DIRECTW) { if (wpipe->pipe_state & PIPE_WANTR) { wpipe->pipe_state &= ~PIPE_WANTR; wakeup(wpipe); @@ -968,8 +974,7 @@ retry: goto error1; } - error = 0; - while (!error && (wpipe->pipe_state & PIPE_DIRECTW)) { + while (wpipe->pipe_map.cnt != 0) { if (wpipe->pipe_state & PIPE_EOF) { pipe_destroy_write_buffer(wpipe); pipeselwakeup(wpipe); @@ -987,20 +992,19 @@ retry: error = msleep(wpipe, PIPE_MTX(wpipe), PRIBIO | PCATCH, "pipdwt", 0); pipelock(wpipe, 0); + if (error != 0) + break; } if (wpipe->pipe_state & PIPE_EOF) error = EPIPE; - if (wpipe->pipe_state & PIPE_DIRECTW) { - /* - * this bit of trickery substitutes a kernel buffer for - * the process that might be going away. - */ + if (error == EINTR || error == ERESTART) pipe_clone_write_buffer(wpipe); - } else { + else pipe_destroy_write_buffer(wpipe); - } pipeunlock(wpipe); + KASSERT((wpipe->pipe_state & PIPE_DIRECTW) == 0, + ("pipe %p leaked PIPE_DIRECTW", wpipe)); return (error); error1: