From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FE10C10F25 for ; Sat, 7 Mar 2020 01:49:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4A4B20705 for ; Sat, 7 Mar 2020 01:49:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726307AbgCGBth (ORCPT ); Fri, 6 Mar 2020 20:49:37 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:11193 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726237AbgCGBth (ORCPT ); Fri, 6 Mar 2020 20:49:37 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id E87C7C3E6D00EC160187; Sat, 7 Mar 2020 09:49:34 +0800 (CST) Received: from [127.0.0.1] (10.133.210.141) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.487.0; Sat, 7 Mar 2020 09:49:26 +0800 Subject: Re: [PATCH 4.4.y v2] crypto: algif_skcipher - use ZERO_OR_NULL_PTR in skcipher_recvmsg_async To: Sasha Levin CC: , , , , References: <20200305085755.22730-1-yangerkun@huawei.com> <20200306133941.GQ21491@sasha-vm> From: yangerkun Message-ID: <8bb5b0d7-4232-14cb-49c7-a3cc348645ae@huawei.com> Date: Sat, 7 Mar 2020 09:49:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20200306133941.GQ21491@sasha-vm> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.133.210.141] X-CFilter-Loop: Reflected Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On 2020/3/6 21:39, Sasha Levin wrote: > On Thu, Mar 05, 2020 at 04:57:55PM +0800, yangerkun wrote: >> Nowdays, we trigger a oops: >> ... >> kasan: GPF could be caused by NULL-ptr deref or user memory >> accessgeneral protection fault: 0000 [#1] SMP KASAN >> ... >> Call Trace: >> [] skcipher_recvmsg_async+0x3f1/0x1400 >> x86/../crypto/algif_skcipher.c:543 >> [] skcipher_recvmsg+0x93/0x7f0 >> x86/../crypto/algif_skcipher.c:723 >> [] sock_recvmsg_nosec x86/../net/socket.c:702 [inline] >> [] sock_recvmsg x86/../net/socket.c:710 [inline] >> [] sock_recvmsg+0x94/0xc0 x86/../net/socket.c:705 >> [] sock_read_iter+0x27b/0x3a0 x86/../net/socket.c:787 >> [] aio_run_iocb+0x21b/0x7a0 x86/../fs/aio.c:1520 >> [] io_submit_one x86/../fs/aio.c:1630 [inline] >> [] do_io_submit+0x6b9/0x10b0 x86/../fs/aio.c:1688 >> [] SYSC_io_submit x86/../fs/aio.c:1713 [inline] >> [] SyS_io_submit+0x2d/0x40 x86/../fs/aio.c:1710 >> [] tracesys_phase2+0x90/0x95 >> >> In skcipher_recvmsg_async, we use '!sreq->tsg' to determine does we >> calloc fail. However, kcalloc may return ZERO_SIZE_PTR, and with this, >> the latter sg_init_table will trigger the bug. Fix it be use >> ZERO_OF_NULL_PTR. >> >> This function was introduced with ' commit a596999b7ddf ("crypto: >> algif - change algif_skcipher to be asynchronous")', and has been removed >> with 'commit e870456d8e7c ("crypto: algif_skcipher - overhaul memory >> management")'. >> >> Reported-by: Hulk Robot >> Signed-off-by: yangerkun >> --- >> crypto/algif_skcipher.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> v1->v2: >> update the commit message >> >> diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c >> index d12782dc9683..9bd4691cc5c5 100644 >> --- a/crypto/algif_skcipher.c >> +++ b/crypto/algif_skcipher.c >> @@ -538,7 +538,7 @@ static int skcipher_recvmsg_async(struct socket >> *sock, struct msghdr *msg, >> lock_sock(sk); >> tx_nents = skcipher_all_sg_nents(ctx); >> sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL); >> - if (unlikely(!sreq->tsg)) >> + if (unlikely(ZERO_OR_NULL_PTR(sreq->tsg))) > > I'm a bit confused: kcalloc() will return ZERO_SIZE_PTR for allocations > that ask for 0 bytes, but here we ask for "sizeof(*sg)" bytes, which is > guaranteed to be more than 0, no? Actually, the size need to calloc is (tx_nents * sizeof(*sg)), and tx_nents is 0. >