From patchwork Thu Nov 2 14:21:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Craig Gallek X-Patchwork-Id: 833380 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3ySS1w6Hpmz9t2f for ; Fri, 3 Nov 2017 01:21:24 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933356AbdKBOVX (ORCPT ); Thu, 2 Nov 2017 10:21:23 -0400 Received: from mail-yw0-f194.google.com ([209.85.161.194]:43256 "EHLO mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932312AbdKBOVV (ORCPT ); Thu, 2 Nov 2017 10:21:21 -0400 Received: by mail-yw0-f194.google.com with SMTP id y75so4926972ywg.0 for ; Thu, 02 Nov 2017 07:21:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=rCFvlkx2EH8LRv/hUxDszNQZBCueC6PF4aFQm2FXTBM=; b=nAZOMBBEYFUS0SBIHP0YcCvJB3AeF/rCwXZcf2pQgbR17pFQ9bSmHtkEIbF0pLEdQK /hqin6CzLe2XzFjHDi40s92jRJuHFvs42jWEUXH0b6LTto/cp/ChquuCVr0ePrQPKYfn 1gY16BZi3xJXEXm2G+UdXljr3BkYD7LRNTtlxYzZTfwTR8SpYX6US2ki5DEHr1y1WiHS mUVSmjOwYJKCeO/mr/hzWnXKxgwP+wXsI80WYO5908oR7bBWjaFysFrkynCgBdj3OG4N GwmwfZj/jo4bLCX7TnTRhtS7snvBEDqvnShg/LfDl3RGfMjX7OGp9xNIHH5HLE8r3pjA rsgA== X-Gm-Message-State: AMCzsaWTBT/csTH5hXmloQNLl+r8efrqN3/MlIVv1vZDVKKjZ7AKHN/K hkufmV2m03DyAfK0FMWwlMLhXKLAMtA= X-Google-Smtp-Source: ABhQp+SHXhjcUQlwpcGwI74xq+UaOC8AL4YkY7DBUwawt0Rp94QjQSxRlujeFlwziVxBgp+Y+dIgBg== X-Received: by 10.37.61.129 with SMTP id k123mr2333267yba.44.1509632480933; Thu, 02 Nov 2017 07:21:20 -0700 (PDT) Received: from monkey.nyc.corp.google.com ([100.101.213.10]) by smtp.gmail.com with ESMTPSA id g4sm1416022ywe.71.2017.11.02.07.21.20 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 02 Nov 2017 07:21:20 -0700 (PDT) From: Craig Gallek To: Alexei Starovoitov , "David S . Miller" Cc: netdev@vger.kernel.org Subject: [PATCH net-next] bpf: fix verifier NULL pointer dereference Date: Thu, 2 Nov 2017 10:21:19 -0400 Message-Id: <20171102142119.13894-1-kraigatgoog@gmail.com> X-Mailer: git-send-email 2.15.0.403.gc27cc4dac6-goog Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Craig Gallek do_check() can fail early without allocating env->cur_state under memory pressure. Syzkaller found the stack below on the linux-next tree because of this. kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 27062 Comm: syz-executor5 Not tainted 4.14.0-rc7+ #106 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801c2c74700 task.stack: ffff8801c3e28000 RIP: 0010:free_verifier_state kernel/bpf/verifier.c:347 [inline] RIP: 0010:bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533 RSP: 0018:ffff8801c3e2f5c8 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 00000000fffffff4 RCX: 0000000000000000 RDX: 0000000000000070 RSI: ffffffff817d5aa9 RDI: 0000000000000380 RBP: ffff8801c3e2f668 R08: 0000000000000000 R09: 1ffff100387c5d9f R10: 00000000218c4e80 R11: ffffffff85b34380 R12: ffff8801c4dc6a28 R13: 0000000000000000 R14: ffff8801c4dc6a00 R15: ffff8801c4dc6a20 FS: 00007f311079b700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004d4a24 CR3: 00000001cbcd0000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: bpf_prog_load+0xcbb/0x18e0 kernel/bpf/syscall.c:1166 SYSC_bpf kernel/bpf/syscall.c:1690 [inline] SyS_bpf+0xae9/0x4620 kernel/bpf/syscall.c:1652 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x452869 RSP: 002b:00007f311079abe8 EFLAGS: 00000212 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452869 RDX: 0000000000000030 RSI: 0000000020168000 RDI: 0000000000000005 RBP: 00007f311079aa20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b7550 R13: 00007f311079ab58 R14: 00000000004b7560 R15: 0000000000000000 Code: df 48 c1 ea 03 80 3c 02 00 0f 85 e6 0b 00 00 4d 8b 6e 20 48 b8 00 00 00 00 00 fc ff df 49 8d bd 80 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 b6 0b 00 00 49 8b bd 80 03 00 00 e8 d6 0c 26 RIP: free_verifier_state kernel/bpf/verifier.c:347 [inline] RSP: ffff8801c3e2f5c8 RIP: bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533 RSP: ffff8801c3e2f5c8 ---[ end trace c8d37f339dc64004 ]--- Fixes: 638f5b90d460 ("bpf: reduce verifier memory consumption") Fixes: 1969db47f8d0 ("bpf: fix verifier memory leaks") Signed-off-by: Craig Gallek --- kernel/bpf/verifier.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 530b68550fd2..199ae7ccb2b7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4530,8 +4530,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr) env->allow_ptr_leaks = capable(CAP_SYS_ADMIN); ret = do_check(env); - free_verifier_state(env->cur_state, true); - env->cur_state = NULL; + if (env->cur_state) { + free_verifier_state(env->cur_state, true); + env->cur_state = NULL; + } skip_full_check: while (!pop_stack(env, NULL, NULL));