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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93AD9C4332F for ; Wed, 2 Nov 2022 02:59:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 066316B0071; Tue, 1 Nov 2022 22:59:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0160E6B0072; Tue, 1 Nov 2022 22:59:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1FAE6B0073; Tue, 1 Nov 2022 22:59:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id D20B46B0071 for ; Tue, 1 Nov 2022 22:59:52 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B1DDC40237 for ; Wed, 2 Nov 2022 02:59:52 +0000 (UTC) X-FDA: 80086997424.15.FCE077F Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf22.hostedemail.com (Postfix) with ESMTP id 07C5FC0004 for ; Wed, 2 Nov 2022 02:59:49 +0000 (UTC) Received: from canpemm500005.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4N2BSZ5f6Vz15MHd; Wed, 2 Nov 2022 10:59:42 +0800 (CST) Received: from [10.174.178.197] (10.174.178.197) by canpemm500005.china.huawei.com (7.192.104.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 2 Nov 2022 10:59:44 +0800 Message-ID: Date: Wed, 2 Nov 2022 10:59:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: [PATCH -next] bpf, test_run: fix alignment problem in bpf_prog_test_run_skb() To: Daniel Borkmann , , , , CC: , , , , , , , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Linux MM , , , , References: <20221101040440.3637007-1-zhongbaisong@huawei.com> From: zhongbaisong Organization: huawei In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.197] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500005.china.huawei.com (7.192.104.229) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667357990; a=rsa-sha256; cv=none; b=F/lxur0RekqXXek12EVcYPJUyTGOGndIEa8YsKD1GnRYdhvoy7sxipTY64y3sfXh/oSp/Y jzbz7BLVmIobZXRuRn8DxcpMwIGEgLgdwoGU4wcHVa7Cw6zW2EjWRVOs0aRrKqtxFcE12E 8e2/tBxktN3krWNbc+bFoqzOAWTupWY= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf22.hostedemail.com: domain of zhongbaisong@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=zhongbaisong@huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667357990; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KQvWv3mC3+foxrp/BeHsNj2yAa1JuS/UTbWcp2YdeHg=; b=btT3D+xjcPQhvnEWvhz/0ULAmZm7UuNChQu6Ysa+bm6BYMyrdSPr9dimIwBB+afudg0tvn o2vergWaqnUde1V12jq1wNfdJ6LEyHEL0Rz6GfKcn/jVSAWO7Zocc8h76jXwOBz/54yBaT SlL7LlJPeXT56dtuHWtjNzRaIQtPzDI= X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 07C5FC0004 X-Rspam-User: Authentication-Results: imf22.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf22.hostedemail.com: domain of zhongbaisong@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=zhongbaisong@huawei.com X-Stat-Signature: ecj3umnqxfucccp7zdysc1acrsqezun3 X-HE-Tag: 1667357989-677463 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/11/2 0:45, Daniel Borkmann wrote: > [ +kfence folks ] + cc: Alexander Potapenko, Marco Elver, Dmitry Vyukov Do you have any suggestions about this problem? Thanks, . > > On 11/1/22 5:04 AM, Baisong Zhong wrote: >> Recently, we got a syzkaller problem because of aarch64 >> alignment fault if KFENCE enabled. >> >> When the size from user bpf program is an odd number, like >> 399, 407, etc, it will cause skb shard info's alignment access, >> as seen below: >> >> BUG: KFENCE: use-after-free read in __skb_clone+0x23c/0x2a0 >> net/core/skbuff.c:1032 >> >> Use-after-free read at 0xffff6254fffac077 (in kfence-#213): >>   __lse_atomic_add arch/arm64/include/asm/atomic_lse.h:26 [inline] >>   arch_atomic_add arch/arm64/include/asm/atomic.h:28 [inline] >>   arch_atomic_inc include/linux/atomic-arch-fallback.h:270 [inline] >>   atomic_inc include/asm-generic/atomic-instrumented.h:241 [inline] >>   __skb_clone+0x23c/0x2a0 net/core/skbuff.c:1032 >>   skb_clone+0xf4/0x214 net/core/skbuff.c:1481 >>   ____bpf_clone_redirect net/core/filter.c:2433 [inline] >>   bpf_clone_redirect+0x78/0x1c0 net/core/filter.c:2420 >>   bpf_prog_d3839dd9068ceb51+0x80/0x330 >>   bpf_dispatcher_nop_func include/linux/bpf.h:728 [inline] >>   bpf_test_run+0x3c0/0x6c0 net/bpf/test_run.c:53 >>   bpf_prog_test_run_skb+0x638/0xa7c net/bpf/test_run.c:594 >>   bpf_prog_test_run kernel/bpf/syscall.c:3148 [inline] >>   __do_sys_bpf kernel/bpf/syscall.c:4441 [inline] >>   __se_sys_bpf+0xad0/0x1634 kernel/bpf/syscall.c:4381 >> >> kfence-#213: 0xffff6254fffac000-0xffff6254fffac196, size=407, >> cache=kmalloc-512 >> >> allocated by task 15074 on cpu 0 at 1342.585390s: >>   kmalloc include/linux/slab.h:568 [inline] >>   kzalloc include/linux/slab.h:675 [inline] >>   bpf_test_init.isra.0+0xac/0x290 net/bpf/test_run.c:191 >>   bpf_prog_test_run_skb+0x11c/0xa7c net/bpf/test_run.c:512 >>   bpf_prog_test_run kernel/bpf/syscall.c:3148 [inline] >>   __do_sys_bpf kernel/bpf/syscall.c:4441 [inline] >>   __se_sys_bpf+0xad0/0x1634 kernel/bpf/syscall.c:4381 >>   __arm64_sys_bpf+0x50/0x60 kernel/bpf/syscall.c:4381 >> >> To fix the problem, we round up allocations with kmalloc_size_roundup() >> so that build_skb()'s use of kize() is always alignment and no special >> handling of the memory is needed by KFENCE. >> >> Fixes: 1cf1cae963c2 ("bpf: introduce BPF_PROG_TEST_RUN command") >> Signed-off-by: Baisong Zhong >> --- >>   net/bpf/test_run.c | 1 + >>   1 file changed, 1 insertion(+) >> >> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c >> index 13d578ce2a09..058b67108873 100644 >> --- a/net/bpf/test_run.c >> +++ b/net/bpf/test_run.c >> @@ -774,6 +774,7 @@ static void *bpf_test_init(const union bpf_attr >> *kattr, u32 user_size, >>       if (user_size > size) >>           return ERR_PTR(-EMSGSIZE); >> +    size = kmalloc_size_roundup(size); >>       data = kzalloc(size + headroom + tailroom, GFP_USER); > > The fact that you need to do this roundup on call sites feels broken, no? > Was there some discussion / consensus that now all k*alloc() call sites > would need to be fixed up? Couldn't this be done transparently in k*alloc() > when KFENCE is enabled? I presume there may be lots of other such occasions > in the kernel where similar issue triggers, fixing up all call-sites feels > like ton of churn compared to api-internal, generic fix. > >>       if (!data) >>           return ERR_PTR(-ENOMEM); >> > > Thanks, > Daniel >