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=-10.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 C6B06C0650E for ; Mon, 1 Jul 2019 14:48:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 98EE12064B for ; Mon, 1 Jul 2019 14:48:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brauner.io header.i=@brauner.io header.b="Amh80EQI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729828AbfGAOsb (ORCPT ); Mon, 1 Jul 2019 10:48:31 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:36964 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727714AbfGAOsa (ORCPT ); Mon, 1 Jul 2019 10:48:30 -0400 Received: by mail-io1-f68.google.com with SMTP id e5so29436705iok.4 for ; Mon, 01 Jul 2019 07:48:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brauner.io; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=wSejyUTe512azskM/IpIonqmiTNyrrIhcYfEz7ZQPjg=; b=Amh80EQIE49mNx9Nt5N0ylXvUZ2MrcRTYm2KR2D157wXvQyeSLVA8VlKOo6HCYlsVv W23eGT61hICOIQ3bjR5NKp4fjdId/wptUd05Q033kzuhFonOb6/Yva2M/n5TYLQ6ppkN k9B7LaBCd48qj/mcNSE2lOgvBUgCE2zuhvJ738SARcfmBrEISS7YU+ngISeIfODKaYDQ 9DRieGXqOYlNXVpyS/jOzNXbrDR2vC1N1DTD3jTmdtU+GaskNmiV+1ZlzdsASB+jCaIe 7YVd29gjERVWMNSYt9DbYW5ZWibrT1S0BRbku1fpZ2VuwhEXmQRC2uHN7Ez3VYiCjf47 aixw== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=wSejyUTe512azskM/IpIonqmiTNyrrIhcYfEz7ZQPjg=; b=Jk60f1bNymjD1q9mdJNii/CVttvPM/j87oD0rFhNsRMCuMy3MbPl2Qe+j5fSffrDyl IiXMbY1DEXa0f4e60E1NuNcEPAkHrmjWNKGn4DvJhu/SPhAD0YT8t3tU1WBLTAue0HbV XZcR5p9SLNIvDHJwl/dfPadUQ3WQ2O1Mnw201d0twebEWCtRrR3m9KDZ0wFlWF9JpF06 J50BsepZyg/6Mftr2NXLuFhiZFJivFZSJ4HUV8d4DPx+yzXg+u/jQ3r6C5aU4DGx5gGf MRPRL1Ps7o1GaUDf2sXxYJlVaD+WdSkPyXnBJM7teQvg+9FxUgb5I8fwOmHXSZR/tXqo 9+Cg== X-Gm-Message-State: APjAAAUU8HBOAUSmAbOpqunTAoEiVx1MEiIAOZgKMq16iCDdlc+HPq6U dIAhHFR/SVR1W170ML/BPwZO7w== X-Google-Smtp-Source: APXvYqzbfDnQnpkfPgPHbXwJBjPBvfaGSnyg+u7fbDEbY7QzQOovqTakzB10tVcti/gaNb7cYVW1lg== X-Received: by 2002:a02:b798:: with SMTP id f24mr17183838jam.97.1561992509632; Mon, 01 Jul 2019 07:48:29 -0700 (PDT) Received: from localhost.localdomain ([208.54.80.252]) by smtp.gmail.com with ESMTPSA id x22sm9062178iob.84.2019.07.01.07.48.22 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 01 Jul 2019 07:48:28 -0700 (PDT) From: Christian Brauner To: syzbot+002e636502bc4b64eb5c@syzkaller.appspotmail.com, viro@zeniv.linux.org.uk, jannh@google.com Cc: akpm@linux-foundation.org, arunks@codeaurora.org, ebiederm@xmission.com, elena.reshetova@intel.com, gregkh@linuxfoundation.org, guro@fb.com, ktsanaktsidis@zendesk.com, linux-kernel@vger.kernel.org, mhocko@suse.com, mingo@kernel.org, peterz@infradead.org, riel@surriel.com, rppt@linux.vnet.ibm.com, scuttimmy@gmail.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, willy@infradead.org, yuehaibing@huawei.com, Christian Brauner Subject: [PATCH] fork: return proper negative error code Date: Mon, 1 Jul 2019 16:48:08 +0200 Message-Id: <20190701144808.6804-1-christian@brauner.io> X-Mailer: git-send-email 2.22.0 In-Reply-To: <000000000000e0dc0d058c9e7142@google.com> References: <000000000000e0dc0d058c9e7142@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Make sure to return a proper negative error code from copy_process() when anon_inode_getfile() fails with CLONE_PIDFD. Otherwise _do_fork() will not detect an error and get_task_pid() will operator on a nonsensical pointer: R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c R13: 00007ffc15fbb0ff R14: 00007ff07e47e9c0 R15: 0000000000000000 kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7990 Comm: syz-executor290 Not tainted 5.2.0-rc6+ #9 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__read_once_size include/linux/compiler.h:194 [inline] RIP: 0010:get_task_pid+0xe1/0x210 kernel/pid.c:372 Code: 89 ff e8 62 27 5f 00 49 8b 07 44 89 f1 4c 8d bc c8 90 01 00 00 eb 0c e8 0d fe 25 00 49 81 c7 38 05 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ff e8 31 27 5f 00 4d 8b 37 e8 f9 47 12 00 RSP: 0018:ffff88808a4a7d78 EFLAGS: 00010203 RAX: 00000000000000a7 RBX: dffffc0000000000 RCX: ffff888088180600 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88808a4a7d90 R08: ffffffff814fb3a8 R09: ffffed1015d66bf8 R10: ffffed1015d66bf8 R11: 1ffff11015d66bf7 R12: 0000000000041ffc R13: 1ffff11011494fbc R14: 0000000000000000 R15: 000000000000053d FS: 00007ff07e47e700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004b5100 CR3: 0000000094df2000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: _do_fork+0x1b9/0x5f0 kernel/fork.c:2360 __do_sys_clone kernel/fork.c:2454 [inline] __se_sys_clone kernel/fork.c:2448 [inline] __x64_sys_clone+0xc1/0xd0 kernel/fork.c:2448 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe Link: https://lore.kernel.org/lkml/000000000000e0dc0d058c9e7142@google.com Reported-and-tested-by: syzbot+002e636502bc4b64eb5c@syzkaller.appspotmail.com Fixes: 6fd2fe494b17 ("copy_process(): don't use ksys_close() on cleanups") Cc: Jann Horn Cc: Al Viro Signed-off-by: Christian Brauner --- kernel/fork.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/fork.c b/kernel/fork.c index 61667909ce83..fe83343da24b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2036,6 +2036,7 @@ static __latent_entropy struct task_struct *copy_process( O_RDWR | O_CLOEXEC); if (IS_ERR(pidfile)) { put_unused_fd(pidfd); + retval = PTR_ERR(pidfile); goto bad_fork_free_pid; } get_pid(pid); /* held by pidfile now */ -- 2.22.0