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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33C54C352A1 for ; Tue, 6 Dec 2022 09:39:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230450AbiLFJjC (ORCPT ); Tue, 6 Dec 2022 04:39:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234156AbiLFJi7 (ORCPT ); Tue, 6 Dec 2022 04:38:59 -0500 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EAAC1AD99; Tue, 6 Dec 2022 01:38:57 -0800 (PST) Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2B68NiHI017013; Tue, 6 Dec 2022 09:38:56 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=corp-2022-7-12; bh=h+xqY3ap6uUHi01HvJo5PCdAUlQP/OuCOPGu3xuefWk=; b=U6bRebwq0a09eqoYyMUBMzvDDuwlnT3h2M5neEXXJTjqnJUyjSZL82rFrVrIJGNRuFuw mY51NhaY9FsGHfoY22j9HVv4THWFsxhfi4Bnd1jhww8Wx0ODlHbxJaHkNzyTxWUhTzZq eza7QQfbD7WwT/nK3cfckhC5vH7baAwGYnZKmMiDFSbR3h6RvEUzFDRlQA7t1qpaHtTV b57TX+gTY7VlaIDq9c0+McWcVhvm/FtkV/xauiQIG9zoaCVlx0PsUJVJxK0c70KERHFp r20RA8VJ6vPT2zPCfHA336k4/37bA7JcksXw/pWU1Ex3OhqolgmqXGbs8L7dIFFVm/uV /g== Received: from phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta03.appoci.oracle.com [138.1.37.129]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3m7ybgpmat-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 06 Dec 2022 09:38:55 +0000 Received: from pps.filterd (phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (8.17.1.5/8.17.1.5) with ESMTP id 2B67VZf2031092; Tue, 6 Dec 2022 09:38:47 GMT Received: from pps.reinject (localhost [127.0.0.1]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3m8ua0ahce-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 06 Dec 2022 09:38:47 +0000 Received: from phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 2B69clcE006666; Tue, 6 Dec 2022 09:38:47 GMT Received: from ca-dev112.us.oracle.com (ca-dev112.us.oracle.com [10.129.136.47]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 3m8ua0ahc9-1; Tue, 06 Dec 2022 09:38:47 +0000 From: Harshit Mogalapalli Cc: harshit.m.mogalapalli@oracle.com, harshit.m.mogalapalli@gmail.com, vegard.nossum@oracle.com, george.kennedy@oracle.com, darren.kenny@oracle.com, syzkaller , Jens Axboe , Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] io_uring: Fix a null-ptr-deref in io_tctx_exit_cb() Date: Tue, 6 Dec 2022 01:38:32 -0800 Message-Id: <20221206093833.3812138-1-harshit.m.mogalapalli@oracle.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.923,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-12-06_05,2022-12-05_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=901 mlxscore=0 adultscore=0 phishscore=0 suspectscore=0 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2212060079 X-Proofpoint-ORIG-GUID: pYNp8N-3mGfidp7miOcVNRWjSqIG7PZh X-Proofpoint-GUID: pYNp8N-3mGfidp7miOcVNRWjSqIG7PZh To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Syzkaller reports a NULL deref bug as follows: BUG: KASAN: null-ptr-deref in io_tctx_exit_cb+0x53/0xd3 Read of size 4 at addr 0000000000000138 by task file1/1955 CPU: 1 PID: 1955 Comm: file1 Not tainted 6.1.0-rc7-00103-gef4d3ea40565 #75 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 Call Trace: dump_stack_lvl+0xcd/0x134 ? io_tctx_exit_cb+0x53/0xd3 kasan_report+0xbb/0x1f0 ? io_tctx_exit_cb+0x53/0xd3 kasan_check_range+0x140/0x190 io_tctx_exit_cb+0x53/0xd3 task_work_run+0x164/0x250 ? task_work_cancel+0x30/0x30 get_signal+0x1c3/0x2440 ? lock_downgrade+0x6e0/0x6e0 ? lock_downgrade+0x6e0/0x6e0 ? exit_signals+0x8b0/0x8b0 ? do_raw_read_unlock+0x3b/0x70 ? do_raw_spin_unlock+0x50/0x230 arch_do_signal_or_restart+0x82/0x2470 ? kmem_cache_free+0x260/0x4b0 ? putname+0xfe/0x140 ? get_sigframe_size+0x10/0x10 ? do_execveat_common.isra.0+0x226/0x710 ? lockdep_hardirqs_on+0x79/0x100 ? putname+0xfe/0x140 ? do_execveat_common.isra.0+0x238/0x710 exit_to_user_mode_prepare+0x15f/0x250 syscall_exit_to_user_mode+0x19/0x50 do_syscall_64+0x42/0xb0 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0023:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 002b:00000000fffb7790 EFLAGS: 00000200 ORIG_RAX: 000000000000000b RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Kernel panic - not syncing: panic_on_warn set ... Add a NULL check on tctx to prevent this. Fixes: d56d938b4bef ("io_uring: do ctx initiated file note removal") Reported-by: syzkaller Signed-off-by: Harshit Mogalapalli --- Could not find the root cause of this. --- io_uring/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 8840cf3e20f2..20f7d8655b50 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2708,7 +2708,7 @@ static __cold void io_tctx_exit_cb(struct callback_head *cb) * When @in_idle, we're in cancellation and it's racy to remove the * node. It'll be removed by the end of cancellation, just ignore it. */ - if (!atomic_read(&tctx->in_idle)) + if (tctx && !atomic_read(&tctx->in_idle)) io_uring_del_tctx_node((unsigned long)work->ctx); complete(&work->completion); } -- 2.38.1