From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751769AbdJXHrw (ORCPT ); Tue, 24 Oct 2017 03:47:52 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:8978 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751732AbdJXHrt (ORCPT ); Tue, 24 Oct 2017 03:47:49 -0400 From: Chen Feng To: , , , , CC: , , Subject: [PATCH RFC] random: fix syzkaller fuzzer test int overflow Date: Tue, 24 Oct 2017 15:44:17 +0800 Message-ID: <1508831057-64195-1-git-send-email-puck.chen@hisilicon.com> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.184.163.62] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090206.59EEEF5C.0026,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 15e174f6958fe372e48b653b724105df Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [pid:11940,cpu6,syz-executor][flp_ioctl]cmd[0x1] Restart is not permit ================================================================= UBSAN: Undefined behaviour in kernel/linux-4.4/drivers/char/random.c:676:19 signed integer overflow: 2147483645 + 268435455 cannot be represented in type 'int' CPU: 4 PID: 11941 Comm: syz-executor Not tainted 4.4.76+ #2 TGID: 11928 Comm: syz-executor Hardware name: hi3660 (DT) Call trace: [] dump_backtrace+0x0/0x314 [] show_stack+0x1c/0x24 [] dump_stack+0xdc/0x130 [] ubsan_epilogue+0x18/0x6c [] handle_overflow+0x180/0x1d4 [] __ubsan_handle_add_overflow+0x2c/0x34 [] credit_entropy_bits+0x358/0x9a8 [] random_ioctl+0x338/0x384 [] do_vfs_ioctl+0x60c/0xa4c [] SyS_ioctl+0x9c/0xc0 [] el0_svc_naked+0x24/0x28 ================================================================= Signed-off-by: Chen Feng Signed-off-by: Yukun Zhao --- drivers/char/random.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 1ef2640..6f2bd6a 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -699,6 +699,11 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; + if (INT_MAX - nbits < r->entropy_total) { + WARN_ON(1); + return; + } + r->entropy_total += nbits; if (!r->initialized && r->entropy_total > 128) { r->initialized = 1; -- 1.9.1