From patchwork Tue Nov 1 04:04:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baisong Zhong X-Patchwork-Id: 13026640 X-Patchwork-Delegate: bpf@iogearbox.net 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D301DC433FE for ; Tue, 1 Nov 2022 04:04:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229494AbiKAEEp (ORCPT ); Tue, 1 Nov 2022 00:04:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229452AbiKAEEo (ORCPT ); Tue, 1 Nov 2022 00:04:44 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C47B313F9A; Mon, 31 Oct 2022 21:04:42 -0700 (PDT) Received: from canpemm500005.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N1brK2f6GzVj3y; Tue, 1 Nov 2022 11:59:45 +0800 (CST) Received: from huawei.com (10.175.104.82) 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; Tue, 1 Nov 2022 12:04:40 +0800 From: Baisong Zhong To: , , , CC: , , , , , , , Subject: [PATCH -next] bpf, test_run: fix alignment problem in bpf_prog_test_run_skb() Date: Tue, 1 Nov 2022 12:04:40 +0800 Message-ID: <20221101040440.3637007-1-zhongbaisong@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.104.82] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500005.china.huawei.com (7.192.104.229) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net 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); if (!data) return ERR_PTR(-ENOMEM);