Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753799AbcJNJYy (ORCPT ); Fri, 14 Oct 2016 05:24:54 -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 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-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1184 Lines: 41 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; -- 2.10.1