From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752095AbdFNOxA (ORCPT ); Wed, 14 Jun 2017 10:53:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30964 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751065AbdFNOw7 (ORCPT ); Wed, 14 Jun 2017 10:52:59 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 5ED3C2B0A76 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jlayton@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 5ED3C2B0A76 From: Jeff Layton To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jslaby@suse.cz, zhongjiang@huawei.com, bfields@fieldses.org, viro@zeniv.linux.org.uk, dhowells@redhat.com Subject: [PATCH] fs/fcntl: return -ESRCH in f_setown when pid/pgid can't be found Date: Wed, 14 Jun 2017 10:52:55 -0400 Message-Id: <20170614145255.7767-1-jlayton@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 14 Jun 2017 14:52:58 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current implementation of F_SETOWN doesn't properly vet the argument passed in. It never returns an error. If the argument doesn't specify a valid pid/pgid, then we just end up cleaning out the file->f_owner structure. What we really want is to only clean that out only in the case where userland passed in an argument of 0. For anything else, we want to return ESRCH if it doesn't refer to a valid pid. The relevant POSIX spec page is here: http://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html Cc: Jiri Slaby Cc: zhong jiang Signed-off-by: Jeff Layton --- fs/fcntl.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index 693322e28751..afed3b364979 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -112,8 +112,9 @@ EXPORT_SYMBOL(__f_setown); int f_setown(struct file *filp, unsigned long arg, int force) { enum pid_type type; - struct pid *pid; - int who = arg; + struct pid *pid = NULL; + int who = arg, ret = 0; + type = PIDTYPE_PID; if (who < 0) { /* avoid overflow below */ @@ -123,12 +124,19 @@ int f_setown(struct file *filp, unsigned long arg, int force) type = PIDTYPE_PGID; who = -who; } + rcu_read_lock(); - pid = find_vpid(who); - __f_setown(filp, pid, type, force); + if (who) { + pid = find_vpid(who); + if (!pid) + ret = -ESRCH; + } + + if (!ret) + __f_setown(filp, pid, type, force); rcu_read_unlock(); - return 0; + return ret; } EXPORT_SYMBOL(f_setown); -- 2.13.0