From patchwork Mon Jun 24 21:00:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Gunthorpe X-Patchwork-Id: 11014921 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D16DC14B6 for ; Tue, 25 Jun 2019 07:29:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BC7FD1FE8B for ; Tue, 25 Jun 2019 07:29:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A683B28ADC; Tue, 25 Jun 2019 07:29:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2EFC228AD9 for ; Tue, 25 Jun 2019 07:29:52 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 629746E053; Tue, 25 Jun 2019 07:28:05 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by gabe.freedesktop.org (Postfix) with ESMTPS id 83E5E89DE5 for ; Mon, 24 Jun 2019 21:02:07 +0000 (UTC) Received: by mail-wr1-x443.google.com with SMTP id r16so15343100wrl.11 for ; Mon, 24 Jun 2019 14:02:07 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=hG9eEbhO9ZvVI+JAJ4Kr5jKBUZBlX9y3IyF9CExVuM8=; b=h/5XsKSOc9G4jCAyyXS6uEnwO4/skn6DgHcdxTfc4+//j5NvJAhIegh+9DyU4oE2G5 XMH7LLsIoEn4XCG/5MMFm8aWZLyPuMA3AqcG884+RLitGEZ/Ia7tIYJeYgJ2lvq4+82E mlaW9T0njIhNN8uWNxGdhpCnWE7lCd1ls2rwyUgqck2st+DX1/XZXT8Mgtc7FUg/MWS/ wQI5yzuAnVjGh+DCtbUyUew6Doi4OLqH4ui96fop/jHnlRapWCfn8LV8yW7KRy2UUMDK cZ+I0VBGPFAp6KZ87/SvHLOPiy4KLRDOU6aEzGq0arbv/yxp6LYA2vMTEoAXkV4xMEfq +7zg== X-Gm-Message-State: APjAAAUQL1OScjaTvUizvJ+6rTNIXFwjtQ7o6UewTwMIMUwylUVnX2HA Kz7Wmwf1sxvCeCTJmb2hA0xCKQ== X-Google-Smtp-Source: APXvYqxAEk4qQsJeqyqINse+yHJkRouINtL91JL0sEIFqMM29cMWXWeCvzOgl6HwO/QEFlzvN+y93Q== X-Received: by 2002:adf:f186:: with SMTP id h6mr21080937wro.274.1561410126128; Mon, 24 Jun 2019 14:02:06 -0700 (PDT) Received: from ziepe.ca ([66.187.232.66]) by smtp.gmail.com with ESMTPSA id b71sm446129wmb.7.2019.06.24.14.02.02 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 24 Jun 2019 14:02:02 -0700 (PDT) Received: from jgg by jggl.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hfW6C-0001M2-OO; Mon, 24 Jun 2019 18:02:00 -0300 From: Jason Gunthorpe To: Jerome Glisse , Ralph Campbell , John Hubbard , Felix.Kuehling@amd.com Subject: [PATCH v4 hmm 01/12] mm/hmm: fix use after free with struct hmm in the mmu notifiers Date: Mon, 24 Jun 2019 18:00:59 -0300 Message-Id: <20190624210110.5098-2-jgg@ziepe.ca> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190624210110.5098-1-jgg@ziepe.ca> References: <20190624210110.5098-1-jgg@ziepe.ca> MIME-Version: 1.0 X-Mailman-Approved-At: Tue, 25 Jun 2019 07:27:07 +0000 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=hG9eEbhO9ZvVI+JAJ4Kr5jKBUZBlX9y3IyF9CExVuM8=; b=Dfnwj7SRwV2PMmn2U0d+WODdclNP+8MKrJJpQxHP3JU1uHDlj7Em+GRbnOVlGf37aZ x/iFL81waqsH2R/ZDnogOEsWqssPFpPx6ng2iVzd42Ph8pxRGkGdeHnQFn7WXHxychn7 qhcCnDDKKA2XJlL0t9jgEmXK5iD+LSA9ISspJalIOTaGOUy2P3iEqUcWHAlRfr10A2Zi sVektpaLu8hOSGiRgUg+86mxYZntLzr5JZQnXIkn15UuhOjzFImdCeWJqoAaOquAmGLI hpzcweH8Q2CBVObvgPXPT94/km2oYbyVknkNINwL80SwNwAFFuHpdFRRunzkNVq5yivf 2PaQ== X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrea Arcangeli , Philip Yang , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, linux-mm@kvack.org, Jason Gunthorpe , dri-devel@lists.freedesktop.org, Ira Weiny , Christoph Hellwig , Ben Skeggs Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Jason Gunthorpe mmu_notifier_unregister_no_release() is not a fence and the mmu_notifier system will continue to reference hmm->mn until the srcu grace period expires. Resulting in use after free races like this: CPU0 CPU1 __mmu_notifier_invalidate_range_start() srcu_read_lock hlist_for_each () // mn == hmm->mn hmm_mirror_unregister() hmm_put() hmm_free() mmu_notifier_unregister_no_release() hlist_del_init_rcu(hmm-mn->list) mn->ops->invalidate_range_start(mn, range); mm_get_hmm() mm->hmm = NULL; kfree(hmm) mutex_lock(&hmm->lock); Use SRCU to kfree the hmm memory so that the notifiers can rely on hmm existing. Get the now-safe hmm struct through container_of and directly check kref_get_unless_zero to lock it against free. Signed-off-by: Jason Gunthorpe Reviewed-by: Ira Weiny Reviewed-by: John Hubbard Reviewed-by: Ralph Campbell Reviewed-by: Christoph Hellwig Tested-by: Philip Yang --- v2: - Spell 'free' properly (Jerome/Ralph) v3: - Have only one clearer comment about kref_get_unless_zero (John) --- include/linux/hmm.h | 1 + mm/hmm.c | 23 +++++++++++++++++------ 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 7007123842ba76..cb01cf1fa3c08b 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -93,6 +93,7 @@ struct hmm { struct mmu_notifier mmu_notifier; struct rw_semaphore mirrors_sem; wait_queue_head_t wq; + struct rcu_head rcu; long notifiers; bool dead; }; diff --git a/mm/hmm.c b/mm/hmm.c index 826816ab237799..f6956d78e3cb25 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -104,6 +104,11 @@ static struct hmm *hmm_get_or_create(struct mm_struct *mm) return NULL; } +static void hmm_free_rcu(struct rcu_head *rcu) +{ + kfree(container_of(rcu, struct hmm, rcu)); +} + static void hmm_free(struct kref *kref) { struct hmm *hmm = container_of(kref, struct hmm, kref); @@ -116,7 +121,7 @@ static void hmm_free(struct kref *kref) mm->hmm = NULL; spin_unlock(&mm->page_table_lock); - kfree(hmm); + mmu_notifier_call_srcu(&hmm->rcu, hmm_free_rcu); } static inline void hmm_put(struct hmm *hmm) @@ -144,10 +149,14 @@ void hmm_mm_destroy(struct mm_struct *mm) static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm) { - struct hmm *hmm = mm_get_hmm(mm); + struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier); struct hmm_mirror *mirror; struct hmm_range *range; + /* Bail out if hmm is in the process of being freed */ + if (!kref_get_unless_zero(&hmm->kref)) + return; + /* Report this HMM as dying. */ hmm->dead = true; @@ -185,13 +194,14 @@ static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm) static int hmm_invalidate_range_start(struct mmu_notifier *mn, const struct mmu_notifier_range *nrange) { - struct hmm *hmm = mm_get_hmm(nrange->mm); + struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier); struct hmm_mirror *mirror; struct hmm_update update; struct hmm_range *range; int ret = 0; - VM_BUG_ON(!hmm); + if (!kref_get_unless_zero(&hmm->kref)) + return 0; update.start = nrange->start; update.end = nrange->end; @@ -236,9 +246,10 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn, static void hmm_invalidate_range_end(struct mmu_notifier *mn, const struct mmu_notifier_range *nrange) { - struct hmm *hmm = mm_get_hmm(nrange->mm); + struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier); - VM_BUG_ON(!hmm); + if (!kref_get_unless_zero(&hmm->kref)) + return; mutex_lock(&hmm->lock); hmm->notifiers--;