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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 02347C677D4 for ; Mon, 8 Oct 2018 18:44:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0D96214C4 for ; Mon, 8 Oct 2018 18:44:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="bo2TD4mi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0D96214C4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730803AbeJIB5o (ORCPT ); Mon, 8 Oct 2018 21:57:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:45676 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730397AbeJIB5n (ORCPT ); Mon, 8 Oct 2018 21:57:43 -0400 Received: from localhost (ip-213-127-77-176.ip.prioritytelecom.net [213.127.77.176]) (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 3BECA21479; Mon, 8 Oct 2018 18:44:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1539024277; bh=efZesNdxQHWR2IZQN9fLy9U0BAe4W6mP2rOJFhTi9gU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bo2TD4miXoPV05678/mV3sqyU+0+L+yyCMu5n9/glcDMu9rRVyOyXHAAPtX+tJ/nh DGkM46UjwicBE9Tazzwo98IHXjEfZE7DH152/N5JYwmhIwT0CVI03dLUc5fiXxzL05 cSuuOQEpz4i+d3+TD4llf7Z2C3k3TzVjF3ZU/CVI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Steve Wise , Sagi Grimberg , Christoph Hellwig , Sasha Levin Subject: [PATCH 4.14 57/94] nvmet-rdma: fix possible bogus dereference under heavy load Date: Mon, 8 Oct 2018 20:31:38 +0200 Message-Id: <20181008175608.621569789@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20181008175605.067676667@linuxfoundation.org> References: <20181008175605.067676667@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sagi Grimberg [ Upstream commit 8407879c4e0d7731f6e7e905893cecf61a7762c7 ] Currently we always repost the recv buffer before we send a response capsule back to the host. Since ordering is not guaranteed for send and recv completions, it is posible that we will receive a new request from the host before we got a send completion for the response capsule. Today, we pre-allocate 2x rsps the length of the queue, but in reality, under heavy load there is nothing that is really preventing the gap to expand until we exhaust all our rsps. To fix this, if we don't have any pre-allocated rsps left, we dynamically allocate a rsp and make sure to free it when we are done. If under memory pressure we fail to allocate a rsp, we silently drop the command and wait for the host to retry. Reported-by: Steve Wise Tested-by: Steve Wise Signed-off-by: Sagi Grimberg [hch: dropped a superflous assignment] Signed-off-by: Christoph Hellwig Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/nvme/target/rdma.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) --- a/drivers/nvme/target/rdma.c +++ b/drivers/nvme/target/rdma.c @@ -65,6 +65,7 @@ struct nvmet_rdma_rsp { struct nvmet_req req; + bool allocated; u8 n_rdma; u32 flags; u32 invalidate_rkey; @@ -167,11 +168,19 @@ nvmet_rdma_get_rsp(struct nvmet_rdma_que unsigned long flags; spin_lock_irqsave(&queue->rsps_lock, flags); - rsp = list_first_entry(&queue->free_rsps, + rsp = list_first_entry_or_null(&queue->free_rsps, struct nvmet_rdma_rsp, free_list); - list_del(&rsp->free_list); + if (likely(rsp)) + list_del(&rsp->free_list); spin_unlock_irqrestore(&queue->rsps_lock, flags); + if (unlikely(!rsp)) { + rsp = kmalloc(sizeof(*rsp), GFP_KERNEL); + if (unlikely(!rsp)) + return NULL; + rsp->allocated = true; + } + return rsp; } @@ -180,6 +189,11 @@ nvmet_rdma_put_rsp(struct nvmet_rdma_rsp { unsigned long flags; + if (rsp->allocated) { + kfree(rsp); + return; + } + spin_lock_irqsave(&rsp->queue->rsps_lock, flags); list_add_tail(&rsp->free_list, &rsp->queue->free_rsps); spin_unlock_irqrestore(&rsp->queue->rsps_lock, flags); @@ -756,6 +770,15 @@ static void nvmet_rdma_recv_done(struct cmd->queue = queue; rsp = nvmet_rdma_get_rsp(queue); + if (unlikely(!rsp)) { + /* + * we get here only under memory pressure, + * silently drop and have the host retry + * as we can't even fail it. + */ + nvmet_rdma_post_recv(queue->dev, cmd); + return; + } rsp->queue = queue; rsp->cmd = cmd; rsp->flags = 0;