From patchwork Fri Oct 14 09:23:41 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Slaby X-Patchwork-Id: 9376291 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 554C86075E for ; Fri, 14 Oct 2016 09:24:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4626F2A562 for ; Fri, 14 Oct 2016 09:24:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3AF972A564; Fri, 14 Oct 2016 09:24:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9C2EA2A563 for ; Fri, 14 Oct 2016 09:24:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753676AbcJNJYt (ORCPT ); Fri, 14 Oct 2016 05:24:49 -0400 Received: from mx2.suse.de ([195.135.220.15]:42206 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751547AbcJNJYV (ORCPT ); Fri, 14 Oct 2016 05:24:21 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id CF2FAAC7C; Fri, 14 Oct 2016 09:23:43 +0000 (UTC) From: Jiri Slaby To: viro@zeniv.linux.org.uk Cc: linux-kernel@vger.kernel.org, Jiri Slaby , Jeff Layton , "J. Bruce Fields" , linux-fsdevel@vger.kernel.org Subject: [PATCH] fs: fcntl, avoid undefined behaviour Date: Fri, 14 Oct 2016 11:23:41 +0200 Message-Id: <20161014092342.25546-1-jslaby@suse.cz> X-Mailer: git-send-email 2.10.1 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP fcntl(0, F_SETOWN, 0x80000000) triggers: UBSAN: Undefined behaviour in fs/fcntl.c:118:7 negation of -2147483648 cannot be represented in type 'int': CPU: 1 PID: 18261 Comm: syz-executor Not tainted 4.8.1-0-syzkaller #1 ... Call Trace: ... [] ? f_setown+0x1d8/0x200 [] ? SyS_fcntl+0x999/0xf30 [] ? entry_SYSCALL_64_fastpath+0x23/0xc1 Fix that by checking the arg parameter properly (against INT_MAX) and return immediatelly in case it is wrong. No error is returned, the same as in other cases. Signed-off-by: Jiri Slaby Cc: Jeff Layton Cc: "J. Bruce Fields" Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org --- fs/fcntl.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/fcntl.c b/fs/fcntl.c index 350a2c8cfd28..bfc3b040d956 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -112,6 +112,10 @@ void f_setown(struct file *filp, unsigned long arg, int force) enum pid_type type; struct pid *pid; int who = arg; + + if (arg > INT_MAX) + return; + type = PIDTYPE_PID; if (who < 0) { type = PIDTYPE_PGID;