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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 06791C43381 for ; Fri, 22 Mar 2019 12:46:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C127E218E2 for ; Fri, 22 Mar 2019 12:46:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553258760; bh=xf6bnsBR3Du1gFx8HsgVfYsu1NALMO8S2VnRB4ZLLmk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mFNuDdLtjqvHf4dh/xxvTANKETxujUs2TX8GAgJhw7rhibav+lQj51JumYyhgXFN7 qppaRj880HLLYnbQGwW5cVfOPb5XcvLa43HUTlBjbuP6p1/I04sBDYXqbf5RclKWjE Dcsh9BJFZ88532lQBLisO/4fiMME0zVg5ybLVWTY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388003AbfCVMAD (ORCPT ); Fri, 22 Mar 2019 08:00:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:37044 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388015AbfCVL77 (ORCPT ); Fri, 22 Mar 2019 07:59:59 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D533921934; Fri, 22 Mar 2019 11:59:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553255998; bh=xf6bnsBR3Du1gFx8HsgVfYsu1NALMO8S2VnRB4ZLLmk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KFEf57awHzGDfOsBwdBEL+yRJB6arp3WNUwm92YMlcCGESRfVostyENa/XpCiynSQ 11n8/NHwmD/MuPmJbw4b3Fk4ycYF36bbdKb3PGVMEqbH/8uJkSoW92+/HndoaG14rh KI+92AuOBlGPaR8EfJHtXmnb8FAl7tojrr+G2b80= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anoob Soman , Bob Liu , Lee Duncan , "Martin K. Petersen" , Sasha Levin Subject: [PATCH 4.19 078/280] scsi: libiscsi: Fix race between iscsi_xmit_task and iscsi_complete_task Date: Fri, 22 Mar 2019 12:13:51 +0100 Message-Id: <20190322111310.755016174@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111306.356185024@linuxfoundation.org> References: <20190322111306.356185024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 79edd00dc6a96644d76b4a1cb97d94d49e026768 ] When a target sends Check Condition, whilst initiator is busy xmiting re-queued data, could lead to race between iscsi_complete_task() and iscsi_xmit_task() and eventually crashing with the following kernel backtrace. [3326150.987523] ALERT: BUG: unable to handle kernel NULL pointer dereference at 0000000000000078 [3326150.987549] ALERT: IP: [] iscsi_xmit_task+0x2d/0xc0 [libiscsi] [3326150.987571] WARN: PGD 569c8067 PUD 569c9067 PMD 0 [3326150.987582] WARN: Oops: 0002 [#1] SMP [3326150.987593] WARN: Modules linked in: tun nfsv3 nfs fscache dm_round_robin [3326150.987762] WARN: CPU: 2 PID: 8399 Comm: kworker/u32:1 Tainted: G O 4.4.0+2 #1 [3326150.987774] WARN: Hardware name: Dell Inc. PowerEdge R720/0W7JN5, BIOS 2.5.4 01/22/2016 [3326150.987790] WARN: Workqueue: iscsi_q_13 iscsi_xmitworker [libiscsi] [3326150.987799] WARN: task: ffff8801d50f3800 ti: ffff8801f5458000 task.ti: ffff8801f5458000 [3326150.987810] WARN: RIP: e030:[] [] iscsi_xmit_task+0x2d/0xc0 [libiscsi] [3326150.987825] WARN: RSP: e02b:ffff8801f545bdb0 EFLAGS: 00010246 [3326150.987831] WARN: RAX: 00000000ffffffc3 RBX: ffff880282d2ab20 RCX: ffff88026b6ac480 [3326150.987842] WARN: RDX: 0000000000000000 RSI: 00000000fffffe01 RDI: ffff880282d2ab20 [3326150.987852] WARN: RBP: ffff8801f545bdc8 R08: 0000000000000000 R09: 0000000000000008 [3326150.987862] WARN: R10: 0000000000000000 R11: 000000000000fe88 R12: 0000000000000000 [3326150.987872] WARN: R13: ffff880282d2abe8 R14: ffff880282d2abd8 R15: ffff880282d2ac08 [3326150.987890] WARN: FS: 00007f5a866b4840(0000) GS:ffff88028a640000(0000) knlGS:0000000000000000 [3326150.987900] WARN: CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 [3326150.987907] WARN: CR2: 0000000000000078 CR3: 0000000070244000 CR4: 0000000000042660 [3326150.987918] WARN: Stack: [3326150.987924] WARN: ffff880282d2ad58 ffff880282d2ab20 ffff880282d2abe8 ffff8801f545be18 [3326150.987938] WARN: ffffffffa05cea90 ffff880282d2abf8 ffff88026b59cc80 ffff88026b59cc00 [3326150.987951] WARN: ffff88022acf32c0 ffff880289491800 ffff880255a80800 0000000000000400 [3326150.987964] WARN: Call Trace: [3326150.987975] WARN: [] iscsi_xmitworker+0x2f0/0x360 [libiscsi] [3326150.987988] WARN: [] process_one_work+0x1fc/0x3b0 [3326150.987997] WARN: [] worker_thread+0x2a5/0x470 [3326150.988006] WARN: [] ? __schedule+0x648/0x870 [3326150.988015] WARN: [] ? rescuer_thread+0x300/0x300 [3326150.988023] WARN: [] kthread+0xd5/0xe0 [3326150.988031] WARN: [] ? kthread_stop+0x110/0x110 [3326150.988040] WARN: [] ret_from_fork+0x3f/0x70 [3326150.988048] WARN: [] ? kthread_stop+0x110/0x110 [3326150.988127] ALERT: RIP [] iscsi_xmit_task+0x2d/0xc0 [libiscsi] [3326150.988138] WARN: RSP [3326150.988144] WARN: CR2: 0000000000000078 [3326151.020366] WARN: ---[ end trace 1c60974d4678d81b ]--- Commit 6f8830f5bbab ("scsi: libiscsi: add lock around task lists to fix list corruption regression") introduced "taskqueuelock" to fix list corruption during the race, but this wasn't enough. Re-setting of conn->task to NULL, could race with iscsi_xmit_task(). iscsi_complete_task() { .... if (conn->task == task) conn->task = NULL; } conn->task in iscsi_xmit_task() could be NULL and so will be task. __iscsi_get_task(task) will crash (NullPtr de-ref), trying to access refcount. iscsi_xmit_task() { struct iscsi_task *task = conn->task; __iscsi_get_task(task); } This commit will take extra conn->session->back_lock in iscsi_xmit_task() to ensure iscsi_xmit_task() waits for iscsi_complete_task(), if iscsi_complete_task() wins the race. If iscsi_xmit_task() wins the race, iscsi_xmit_task() increments task->refcount (__iscsi_get_task) ensuring iscsi_complete_task() will not iscsi_free_task(). Signed-off-by: Anoob Soman Signed-off-by: Bob Liu Acked-by: Lee Duncan Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin --- drivers/scsi/libiscsi.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c index f78d2e5c1471..4ad61cfa69c0 100644 --- a/drivers/scsi/libiscsi.c +++ b/drivers/scsi/libiscsi.c @@ -1449,7 +1449,13 @@ static int iscsi_xmit_task(struct iscsi_conn *conn) if (test_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx)) return -ENODATA; + spin_lock_bh(&conn->session->back_lock); + if (conn->task == NULL) { + spin_unlock_bh(&conn->session->back_lock); + return -ENODATA; + } __iscsi_get_task(task); + spin_unlock_bh(&conn->session->back_lock); spin_unlock_bh(&conn->session->frwd_lock); rc = conn->session->tt->xmit_task(task); spin_lock_bh(&conn->session->frwd_lock); -- 2.19.1