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,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 9258DC433DF for ; Wed, 24 Jun 2020 16:52:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FA6720899 for ; Wed, 24 Jun 2020 16:52:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NWjR63Oa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405253AbgFXQwM (ORCPT ); Wed, 24 Jun 2020 12:52:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404017AbgFXQvy (ORCPT ); Wed, 24 Jun 2020 12:51:54 -0400 Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C785FC0613ED; Wed, 24 Jun 2020 09:51:52 -0700 (PDT) Received: by mail-wm1-x343.google.com with SMTP id 22so2971588wmg.1; Wed, 24 Jun 2020 09:51:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=SK/e5vP7M6ohq5nkty8Hp7ehFT7bTOqt8+HLXcuKNbU=; b=NWjR63Oa5eenCo3FEW0tIQajmtVUOom0fwJQedcDSdHN6QNteFZCObuoLUxATpP2nm y/QdIZ6MEF+luEyR9IyI9B4Ik2SAqakU5YUtfXde2+TiaGe0SL/uIurMbU7iO+eeR5GD LTLynX9CBiqR0aojZJzXyY10jjIDQWA1q/ZDMDc+Bu3XdTX6NbCTKJ7ODKAZhbtkO3BX 5ec0YjLheYkdFINmLEH4XzVJ3zAC9tvsm4PDOyciWWjXCvNyRhSoM2JGJk9anoni88c4 ubihIt7/p7Sp57LRxt1/n7g9FcOq93heOSf+uJDEW1IsdSKr5BKP87ie61CAzgMMCeon bf4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=SK/e5vP7M6ohq5nkty8Hp7ehFT7bTOqt8+HLXcuKNbU=; b=gZQ/Z9296RQ/9+oktK6dJWp/Ia3MW1x3rTR1Y33rM/KScvdmuMy73iPiNG04M4sM9S yo8nK0h5aZYeFOEoQpZ5cK+XQ/42ygpOOJg8VnfVS6ZOZUsgd/7vdXmr+fSgISyePhuS uSFf3UrM+DqTr3tN8991C86tHAHQQsKzZt4ngr/ugZYM9coJGTj3fau6LG6hqH1f+DXF mTh1mBX09GRunrARv5swOQ2VeOSTJKLJotGivBcVPWHxJ/h1aty7C+lGvSzsNucfHFJX elkKDBsdFL4lRS45vkfFd9UkDSGWHkwHO3qDOOg7Bsw5KaWN3HX6cVVXl3QBl0KCR9ox 8ILw== X-Gm-Message-State: AOAM533pzpUiLP5wUsCOoAUaXmI0mUH+YRzk53lZwGrmEBSFLmT0Vsl9 EjYFB5sxfzOibHpCzdnib1Y= X-Google-Smtp-Source: ABdhPJzjoGAgCdgms0gyBzPVtelZ90wmSdC9lkBXCP8uhk4uONrUcYGH/VL1KIj0q728dJKxckhv2w== X-Received: by 2002:a1c:4989:: with SMTP id w131mr2124051wma.34.1593017511441; Wed, 24 Jun 2020 09:51:51 -0700 (PDT) Received: from localhost.localdomain ([5.100.193.85]) by smtp.gmail.com with ESMTPSA id z16sm18138182wrr.35.2020.06.24.09.51.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 09:51:51 -0700 (PDT) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] io_uring: fix current->mm NULL dereference on exit Date: Wed, 24 Jun 2020 19:50:08 +0300 Message-Id: X-Mailer: git-send-email 2.24.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Don't reissue requests from io_iopoll_reap_events(), the task may not have mm, which ends up with NULL. It's better to kill everything off on exit anyway. [ 677.734670] RIP: 0010:io_iopoll_complete+0x27e/0x630 ... [ 677.734679] Call Trace: [ 677.734695] ? __send_signal+0x1f2/0x420 [ 677.734698] ? _raw_spin_unlock_irqrestore+0x24/0x40 [ 677.734699] ? send_signal+0xf5/0x140 [ 677.734700] io_iopoll_getevents+0x12f/0x1a0 [ 677.734702] io_iopoll_reap_events.part.0+0x5e/0xa0 [ 677.734703] io_ring_ctx_wait_and_kill+0x132/0x1c0 [ 677.734704] io_uring_release+0x20/0x30 [ 677.734706] __fput+0xcd/0x230 [ 677.734707] ____fput+0xe/0x10 [ 677.734709] task_work_run+0x67/0xa0 [ 677.734710] do_exit+0x35d/0xb70 [ 677.734712] do_group_exit+0x43/0xa0 [ 677.734713] get_signal+0x140/0x900 [ 677.734715] do_signal+0x37/0x780 [ 677.734717] ? enqueue_hrtimer+0x41/0xb0 [ 677.734718] ? recalibrate_cpu_khz+0x10/0x10 [ 677.734720] ? ktime_get+0x3e/0xa0 [ 677.734721] ? lapic_next_deadline+0x26/0x30 [ 677.734723] ? tick_program_event+0x4d/0x90 [ 677.734724] ? __hrtimer_get_next_event+0x4d/0x80 [ 677.734726] __prepare_exit_to_usermode+0x126/0x1c0 [ 677.734741] prepare_exit_to_usermode+0x9/0x40 [ 677.734742] idtentry_exit_cond_rcu+0x4c/0x60 [ 677.734743] sysvec_reschedule_ipi+0x92/0x160 [ 677.734744] ? asm_sysvec_reschedule_ipi+0xa/0x20 [ 677.734745] asm_sysvec_reschedule_ipi+0x12/0x20 Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index fb88a537f471..578ec2e39712 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -884,6 +884,7 @@ enum io_mem_account { ACCT_PINNED, }; +static void io_complete_rw_common(struct kiocb *kiocb, long res); static void io_wq_submit_work(struct io_wq_work **workptr); static void io_cqring_fill_event(struct io_kiocb *req, long res); static void io_put_req(struct io_kiocb *req); @@ -1756,6 +1757,14 @@ static void io_iopoll_queue(struct list_head *again) do { req = list_first_entry(again, struct io_kiocb, list); list_del(&req->list); + + /* shouldn't happen unless io_uring is dying, cancel reqs */ + if (unlikely(!current->mm)) { + io_complete_rw_common(&req->rw.kiocb, -EAGAIN); + io_put_req(req); + continue; + } + refcount_inc(&req->refs); io_queue_async_work(req); } while (!list_empty(again)); -- 2.24.0