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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 E3A65C2D0A8 for ; Wed, 23 Sep 2020 10:59:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1A61235FC for ; Wed, 23 Sep 2020 10:59:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="HQWRkFiO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726466AbgIWK7V (ORCPT ); Wed, 23 Sep 2020 06:59:21 -0400 Received: from mx2.suse.de ([195.135.220.15]:45054 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726332AbgIWK7V (ORCPT ); Wed, 23 Sep 2020 06:59:21 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1600858760; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=1xn1j1ph23HtIa7nv0Wybl2itUAORZz/D4Ib5pP7ULE=; b=HQWRkFiOnhyXiGO/Kmb6tYwMphlivQAjHheQlkvX9P09HkbjucBZnbjrI8eGFCmZFAoNPK zsZUqka421AfC9pdkpJwv/H9NSm7Bb8RNh5ZQDek8wRVEne+x0oV5tA8iu0DoZM5LeqU45 xyJpPrx/3J3Dkf9yOAH+AVLJaojd6R0= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BBE11AC79; Wed, 23 Sep 2020 10:59:57 +0000 (UTC) Message-ID: <1600858740.26851.16.camel@suse.com> Subject: usb_control_msg_send() and usb_control_msg_recv() are highly problematic From: Oliver Neukum To: Himadri Pandya , gregKH@linuxfoundation.org, Alan Stern Cc: linux-usb@vger.kernel.org Date: Wed, 23 Sep 2020 12:59:00 +0200 Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi, you probably do not want to hear this. I was out of comission for the last week weeks and I should have looked at this more closely. You may notice that usb_control_msg() for times immemorial has been using GFP_NOIO internally. This is because control messages are needed in a lot of contexts such as SCSI error handling and runtime PM that require GFP_NOIO. IIRC at that time we found ourselves unable to go through all those call chains, so we pulled the nuclear option and slapped a blanket GFP_NOIO on the function. Today I got a patch that outright deleted a memory allocation with GFP_NOIO, so I looked into this. We are making the same mistake we couldn't fix in the past. I am afraid the API has to be changed to include memory flags. And we should do this now while the damage is still within limits. I am preparing patches. Regards Oliver