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 Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 897AEC43219 for ; Tue, 8 Mar 2022 10:08:56 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 354868131E; Tue, 8 Mar 2022 10:08:56 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 28hQdB7cSrJo; Tue, 8 Mar 2022 10:08:55 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp1.osuosl.org (Postfix) with ESMTPS id AFCEB80BDA; Tue, 8 Mar 2022 10:08:54 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 8E769C001D; Tue, 8 Mar 2022 10:08:54 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 5E617C000B for ; Tue, 8 Mar 2022 10:08:53 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 484E760F26 for ; Tue, 8 Mar 2022 10:08:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp3.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=linaro.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HHtPfPYLeD2P for ; Tue, 8 Mar 2022 10:08:52 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.8.0 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by smtp3.osuosl.org (Postfix) with ESMTPS id 05AA260ACF for ; Tue, 8 Mar 2022 10:08:51 +0000 (UTC) Received: by mail-wm1-x336.google.com with SMTP id bg31-20020a05600c3c9f00b00381590dbb33so1126838wmb.3 for ; Tue, 08 Mar 2022 02:08:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=SkUfNfh3Db7trPuKU1cr1xzPGmDu+V01w8HeZZrfZF4=; b=TcEZ7SnCqx+88Ek0cWwzw0I0uG+pFNYXYTSd6/FUBFUNJcDZChkJJ7aym8/zsrh9wP 0WJgPgrTgga9nbrft6Qq3nPhOdr+MPh3ve1ACFwiAtZ1rDXFoxerrnct9JfMVDD9vNBu OVt7YNvg58Lpaq4XSGltz3TE2P1VPLaSGGWj0ekHuYkbs1y0QLp2/q2TKPBPjgaBgYZm FndSCehbwzLESjJjkPoLr143+oqKI3+53ODsNc2UrDsJ7JxHh88NLirt+Z0q4CIxGxz3 Vghz+IB7ZlQCNmZ0+SdIERYZwTdCaLnVmvnqMTFRhkSMoqNHWVB32uO4XfMp6DyYlqXs OZVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=SkUfNfh3Db7trPuKU1cr1xzPGmDu+V01w8HeZZrfZF4=; b=kTK/UhuEUfbgV0FSTuR8X9ceVGXl5g/UTGCmIK5/Ah9V71XSPsOfNlZhlo6qzFulCh X3l0QpBint9zdDDKSXcmazCp9w1adtyYzrySPb0g7K3eL2hSmMl2tNCbnq64gh7HNYrg C1lj0ARyzyFt38xk941LWFVA2B/amCKWj7dDmnXb+FnEUIi8qSr2stIxEVxvWgXiQnni po6GdhQarJc0m9UteeEiAnrJLy3bg0HjMYMVLNfJlTkM5CICGdwPz2GKFPIzd4RqNDNx k0mPA97zJy3JURFPG+E2CjYggiOsLTo7++lwFtGcOmGn+h7ZITzJkjW5S9Mpxc9CA9lw 9KoA== X-Gm-Message-State: AOAM533uQrNg1fAIj3btR5ZZu7Zct7V8EsFH8fUCHlQVzhjdbg31v8/P W6ofmwlmlMjrY/ufYIpT44Y3fg== X-Google-Smtp-Source: ABdhPJyrzL3jGMmbS7hVKMZbspK5xUkBY1M3etbicBcGEMsABnOdM650d1NvL9CixlA6YyPMGo+S2Q== X-Received: by 2002:a1c:6a08:0:b0:388:73a2:1548 with SMTP id f8-20020a1c6a08000000b0038873a21548mr2868053wmc.163.1646734130240; Tue, 08 Mar 2022 02:08:50 -0800 (PST) Received: from google.com (cpc155339-bagu17-2-0-cust87.1-3.cable.virginm.net. [86.27.177.88]) by smtp.gmail.com with ESMTPSA id u14-20020adfed4e000000b001e3323611e5sm12978222wro.26.2022.03.08.02.08.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Mar 2022 02:08:49 -0800 (PST) Date: Tue, 8 Mar 2022 10:08:47 +0000 From: Lee Jones To: Greg KH Subject: Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use Message-ID: References: <20220307191757.3177139-1-lee.jones@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: syzbot+adc3cb32385586bec859@syzkaller.appspotmail.com, kvm@vger.kernel.org, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, virtualization@lists.linux-foundation.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" T24gVHVlLCAwOCBNYXIgMjAyMiwgR3JlZyBLSCB3cm90ZToKCj4gT24gVHVlLCBNYXIgMDgsIDIw MjIgYXQgMDk6MTU6MjdBTSArMDAwMCwgTGVlIEpvbmVzIHdyb3RlOgo+ID4gT24gVHVlLCAwOCBN YXIgMjAyMiwgR3JlZyBLSCB3cm90ZToKPiA+IAo+ID4gPiBPbiBUdWUsIE1hciAwOCwgMjAyMiBh dCAwODoxMDowNkFNICswMDAwLCBMZWUgSm9uZXMgd3JvdGU6Cj4gPiA+ID4gT24gTW9uLCAwNyBN YXIgMjAyMiwgR3JlZyBLSCB3cm90ZToKPiA+ID4gPiAKPiA+ID4gPiA+IE9uIE1vbiwgTWFyIDA3 LCAyMDIyIGF0IDA3OjE3OjU3UE0gKzAwMDAsIExlZSBKb25lcyB3cm90ZToKPiA+ID4gPiA+ID4g dmhvc3RfdnNvY2tfaGFuZGxlX3R4X2tpY2soKSBhbHJlYWR5IGhvbGRzIHRoZSBtdXRleCBkdXJp bmcgaXRzIGNhbGwKPiA+ID4gPiA+ID4gdG8gdmhvc3RfZ2V0X3ZxX2Rlc2MoKS4gIEFsbCB3ZSBo YXZlIHRvIGRvIGhlcmUgaXMgdGFrZSB0aGUgc2FtZSBsb2NrCj4gPiA+ID4gPiA+IGR1cmluZyB2 aXJ0cXVldWUgY2xlYW4tdXAgYW5kIHdlIG1pdGlnYXRlIHRoZSByZXBvcnRlZCBpc3N1ZXMuCj4g PiA+ID4gPiA+IAo+ID4gPiA+ID4gPiBBbHNvIFdBUk4oKSBhcyBhIHByZWNhdXRpb25hcnkgbWVh c3VyZS4gIFRoZSBwdXJwb3NlIG9mIHRoaXMgaXMgdG8KPiA+ID4gPiA+ID4gY2FwdHVyZSBwb3Nz aWJsZSBmdXR1cmUgcmFjZSBjb25kaXRpb25zIHdoaWNoIG1heSBwb3AgdXAgb3ZlciB0aW1lLgo+ ID4gPiA+ID4gPiAKPiA+ID4gPiA+ID4gTGluazogaHR0cHM6Ly9zeXprYWxsZXIuYXBwc3BvdC5j b20vYnVnP2V4dGlkPTI3OTQzMmQzMGQ4MjVlNjNiYTAwCj4gPiA+ID4gPiA+IAo+ID4gPiA+ID4g PiBDYzogPHN0YWJsZUB2Z2VyLmtlcm5lbC5vcmc+Cj4gPiA+ID4gPiA+IFJlcG9ydGVkLWJ5OiBz eXpib3QrYWRjM2NiMzIzODU1ODZiZWM4NTlAc3l6a2FsbGVyLmFwcHNwb3RtYWlsLmNvbQo+ID4g PiA+ID4gPiBTaWduZWQtb2ZmLWJ5OiBMZWUgSm9uZXMgPGxlZS5qb25lc0BsaW5hcm8ub3JnPgo+ ID4gPiA+ID4gPiAtLS0KPiA+ID4gPiA+ID4gIGRyaXZlcnMvdmhvc3Qvdmhvc3QuYyB8IDEwICsr KysrKysrKysKPiA+ID4gPiA+ID4gIDEgZmlsZSBjaGFuZ2VkLCAxMCBpbnNlcnRpb25zKCspCj4g PiA+ID4gPiA+IAo+ID4gPiA+ID4gPiBkaWZmIC0tZ2l0IGEvZHJpdmVycy92aG9zdC92aG9zdC5j IGIvZHJpdmVycy92aG9zdC92aG9zdC5jCj4gPiA+ID4gPiA+IGluZGV4IDU5ZWRiNWExZmZlMjgu LmVmN2UzNzFlM2U2NDkgMTAwNjQ0Cj4gPiA+ID4gPiA+IC0tLSBhL2RyaXZlcnMvdmhvc3Qvdmhv c3QuYwo+ID4gPiA+ID4gPiArKysgYi9kcml2ZXJzL3Zob3N0L3Zob3N0LmMKPiA+ID4gPiA+ID4g QEAgLTY5Myw2ICs2OTMsMTUgQEAgdm9pZCB2aG9zdF9kZXZfY2xlYW51cChzdHJ1Y3Qgdmhvc3Rf ZGV2ICpkZXYpCj4gPiA+ID4gPiA+ICAJaW50IGk7Cj4gPiA+ID4gPiA+ICAKPiA+ID4gPiA+ID4g IAlmb3IgKGkgPSAwOyBpIDwgZGV2LT5udnFzOyArK2kpIHsKPiA+ID4gPiA+ID4gKwkJLyogTm8g d29ya2VycyBzaG91bGQgcnVuIGhlcmUgYnkgZGVzaWduLiBIb3dldmVyLCByYWNlcyBoYXZlCj4g PiA+ID4gPiA+ICsJCSAqIHByZXZpb3VzbHkgb2NjdXJyZWQgd2hlcmUgZHJpdmVycyBoYXZlIGJl ZW4gdW5hYmxlIHRvIGZsdXNoCj4gPiA+ID4gPiA+ICsJCSAqIGFsbCB3b3JrIHByb3Blcmx5IHBy aW9yIHRvIGNsZWFuLXVwLiAgV2l0aG91dCBhIHN1Y2Nlc3NmdWwKPiA+ID4gPiA+ID4gKwkJICog Zmx1c2ggdGhlIGd1ZXN0IHdpbGwgbWFsZnVuY3Rpb24sIGJ1dCBhdm9pZGluZyBob3N0IG1lbW9y eQo+ID4gPiA+ID4gPiArCQkgKiBjb3JydXB0aW9uIGluIHRob3NlIGNhc2VzIGRvZXMgc2VlbSBw cmVmZXJhYmxlLgo+ID4gPiA+ID4gPiArCQkgKi8KPiA+ID4gPiA+ID4gKwkJV0FSTl9PTihtdXRl eF9pc19sb2NrZWQoJmRldi0+dnFzW2ldLT5tdXRleCkpOwo+ID4gPiA+ID4gCj4gPiA+ID4gPiBT byB5b3UgYXJlIHRyYWRpbmcgb25lIHN5emJvdCB0cmlnZ2VyZWQgaXNzdWUgZm9yIGFub3RoZXIg b25lIGluIHRoZQo+ID4gPiA+ID4gZnV0dXJlPyAgOikKPiA+ID4gPiA+IAo+ID4gPiA+ID4gSWYg dGhpcyBldmVyIGNhbiBoYXBwZW4sIGhhbmRsZSBpdCwgYnV0IGRvbid0IGxvZyBpdCB3aXRoIGEg V0FSTl9PTigpIGFzCj4gPiA+ID4gPiB0aGF0IHdpbGwgdHJpZ2dlciB0aGUgcGFuaWMtb24td2Fy biBib3hlcywgYXMgd2VsbCBhcyBzeXpib3QuICBVbmxlc3MKPiA+ID4gPiA+IHlvdSB3YW50IHRo YXQgdG8gaGFwcGVuPwo+ID4gPiA+IAo+ID4gPiA+IE5vLCBTeXpib3QgZG9lc24ndCByZXBvcnQg d2FybmluZ3MsIG9ubHkgQlVHcyBhbmQgbWVtb3J5IGNvcnJ1cHRpb24uCj4gPiA+IAo+ID4gPiBI YXMgaXQgY2hhbmdlZD8gIExhc3QgSSBsb29rZWQsIGl0IGRpZCB0cmlnZ2VyIG9uIFdBUk5fKiBj YWxscywgd2hpY2gKPiA+ID4gaGFzIHJlc3VsdGVkIGluIGEgaHVnZSBudW1iZXIgb2Yga2VybmVs IGZpeGVzIGJlY2F1c2Ugb2YgdGhhdC4KPiA+IAo+ID4gRXZlcnl0aGluZyBpcyBjdXN0b21pc2Fi bGUgaW4gc3l6a2FsbGVyLCBzbyBtYXliZSB0aGVyZSBhcmUgc3BlY2lmaWMKPiA+IGJ1aWxkcyB3 aGljaCBwYW5pY19vbl93YXJuIGVuYWJsZWQsIGJ1dCBub25lIHRoYXQgSSdtIGludm9sdmVkIHdp dGgKPiA+IGRvLgo+IAo+IE1hbnkgc3lzdGVtcyBydW4gd2l0aCBwYW5pYy1vbi13YXJuIChpLmUu IHRoZSBjbG91ZCksIGFzIHRoZXkgd2FudCB0bwo+IGRyb3AgYSBib3ggYW5kIHJlc3RhcnQgaXQg aWYgYW55dGhpbmcgZ29lcyB3cm9uZy4KPiAKPiBUaGF0J3Mgd2h5IHN5emJvdCByZXBvcnRzIG9u IFdBUk5fKiBjYWxscy4gIFRoZXkgc2hvdWxkIG5ldmVyIGJlCj4gcmVhY2hhYmxlIGJ5IHVzZXJz cGFjZSBhY3Rpb25zLgo+IAo+ID4gSGVyZSBmb2xsb3dzIGEgdG9waWNhbCBleGFtcGxlLiAgVGhl IHJlcG9ydCBhYm92ZSBpbiB0aGUgTGluazogdGFnCj4gPiBjb21lcyB3aXRoIGEgY3Jhc2hsb2cg WzBdLiAgSW4gdGhlcmUgeW91IGNhbiBzZWUgdGhlIFdBUk4oKSBhdCB0aGUKPiA+IGJvdHRvbSBv ZiB2aG9zdF9kZXZfY2xlYW51cCgpIHRyaWdnZXIgbWFueSB0aW1lcyBkdWUgdG8gYSBwb3B1bGF0 ZWQKPiA+IChub24tZmx1c2hlZCkgd29ya2VyIGxpc3QsIGJlZm9yZSBmaW5hbGx5IHRyaXBwaW5n IHRoZSBCVUcoKSB3aGljaAo+ID4gdHJpZ2dlcnMgdGhlIHJlcG9ydDoKPiA+IAo+ID4gWzBdIGh0 dHBzOi8vc3l6a2FsbGVyLmFwcHNwb3QuY29tL3RleHQ/dGFnPUNyYXNoTG9nJng9MTZhNjFmY2U3 MDAwMDAKPiAKPiBPaywgc28gYm90aCBoYXBwZW5zIGhlcmUuICBCdXQgZG9uJ3QgYWRkIGEgd2Fy bmluZyBmb3Igc29tZXRoaW5nIHRoYXQKPiBjYW4ndCBoYXBwZW4uICBKdXN0IGhhbmRsZSBpdCBh bmQgbW92ZSBvbi4gIEl0IGxvb2tzIGxpa2UgeW91IGFyZQo+IGhhbmRsaW5nIGl0IGluIHRoaXMg Y29kZSwgc28gcGxlYXNlIGRyb3AgdGhlIFdBUk5fT04oKS4KCkhhcHB5IHRvIG9ibGlnZS4KCkxl dCdzIGdpdmUgTWljaGVhbCBhIGNoYW5jZSB0byBzcGVhaywgdGhlbiBJJ2xsIGZpeC11cCBpZiBo ZSBhZ3JlZXMuCgotLSAKTGVlIEpvbmVzIFvmnY7nkLzmlq9dClByaW5jaXBhbCBUZWNobmljYWwg TGVhZCAtIERldmVsb3BlciBTZXJ2aWNlcwpMaW5hcm8ub3JnIOKUgiBPcGVuIHNvdXJjZSBzb2Z0 d2FyZSBmb3IgQXJtIFNvQ3MKRm9sbG93IExpbmFybzogRmFjZWJvb2sgfCBUd2l0dGVyIHwgQmxv ZwpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpWaXJ0dWFs aXphdGlvbiBtYWlsaW5nIGxpc3QKVmlydHVhbGl6YXRpb25AbGlzdHMubGludXgtZm91bmRhdGlv bi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8v dmlydHVhbGl6YXRpb24= 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69ECEC43217 for ; Tue, 8 Mar 2022 10:08:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345650AbiCHKJt (ORCPT ); Tue, 8 Mar 2022 05:09:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345625AbiCHKJs (ORCPT ); Tue, 8 Mar 2022 05:09:48 -0500 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D120722505 for ; Tue, 8 Mar 2022 02:08:51 -0800 (PST) Received: by mail-wm1-x336.google.com with SMTP id p184-20020a1c29c1000000b0037f76d8b484so1121846wmp.5 for ; Tue, 08 Mar 2022 02:08:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=SkUfNfh3Db7trPuKU1cr1xzPGmDu+V01w8HeZZrfZF4=; b=TcEZ7SnCqx+88Ek0cWwzw0I0uG+pFNYXYTSd6/FUBFUNJcDZChkJJ7aym8/zsrh9wP 0WJgPgrTgga9nbrft6Qq3nPhOdr+MPh3ve1ACFwiAtZ1rDXFoxerrnct9JfMVDD9vNBu OVt7YNvg58Lpaq4XSGltz3TE2P1VPLaSGGWj0ekHuYkbs1y0QLp2/q2TKPBPjgaBgYZm FndSCehbwzLESjJjkPoLr143+oqKI3+53ODsNc2UrDsJ7JxHh88NLirt+Z0q4CIxGxz3 Vghz+IB7ZlQCNmZ0+SdIERYZwTdCaLnVmvnqMTFRhkSMoqNHWVB32uO4XfMp6DyYlqXs OZVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=SkUfNfh3Db7trPuKU1cr1xzPGmDu+V01w8HeZZrfZF4=; b=eSTKqBxLHKAaa3CyebmB31uAmlstk617BPY3ioHb24s0y+A3kilpsFQu1vxOEE61Bf gHgZwsEot/LExuA92NuqelLNd9yPFVlcK33DvkKNM71or0wb8uod1a2YZn/OPIk3Nzqk SPY7Mo+rMa9ZCKhbXkNMx7XCECAp1nFrQ8UzYyv/s9/jgoBqPRlE9u7vtSLVLmXEmvvJ nOn6l2NN7jdbhtyBTC9mNN6alWKuKctxvGhy0EIp8CS8enfvgt08fHttFc1NnlKKcOl1 0tRlRN6uhrYT39bTCdgTKcJh764N4sZqT18X6PrLXJXypA52kFxfWHGs78ICipWQRpvv U9jw== X-Gm-Message-State: AOAM532XL38InvqEuAhEwgb+XpqQcxekP1UUnxXfPGNg3ezJ++VkaxwQ yDpWW/MMkQaws6h+0BRNHVk5Ng== X-Google-Smtp-Source: ABdhPJyrzL3jGMmbS7hVKMZbspK5xUkBY1M3etbicBcGEMsABnOdM650d1NvL9CixlA6YyPMGo+S2Q== X-Received: by 2002:a1c:6a08:0:b0:388:73a2:1548 with SMTP id f8-20020a1c6a08000000b0038873a21548mr2868053wmc.163.1646734130240; Tue, 08 Mar 2022 02:08:50 -0800 (PST) Received: from google.com (cpc155339-bagu17-2-0-cust87.1-3.cable.virginm.net. [86.27.177.88]) by smtp.gmail.com with ESMTPSA id u14-20020adfed4e000000b001e3323611e5sm12978222wro.26.2022.03.08.02.08.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Mar 2022 02:08:49 -0800 (PST) Date: Tue, 8 Mar 2022 10:08:47 +0000 From: Lee Jones To: Greg KH Cc: mst@redhat.com, jasowang@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, stable@vger.kernel.org, syzbot+adc3cb32385586bec859@syzkaller.appspotmail.com Subject: Re: [PATCH 1/1] vhost: Protect the virtqueue from being cleared whilst still in use Message-ID: References: <20220307191757.3177139-1-lee.jones@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 08 Mar 2022, Greg KH wrote: > On Tue, Mar 08, 2022 at 09:15:27AM +0000, Lee Jones wrote: > > On Tue, 08 Mar 2022, Greg KH wrote: > > > > > On Tue, Mar 08, 2022 at 08:10:06AM +0000, Lee Jones wrote: > > > > On Mon, 07 Mar 2022, Greg KH wrote: > > > > > > > > > On Mon, Mar 07, 2022 at 07:17:57PM +0000, Lee Jones wrote: > > > > > > vhost_vsock_handle_tx_kick() already holds the mutex during its call > > > > > > to vhost_get_vq_desc(). All we have to do here is take the same lock > > > > > > during virtqueue clean-up and we mitigate the reported issues. > > > > > > > > > > > > Also WARN() as a precautionary measure. The purpose of this is to > > > > > > capture possible future race conditions which may pop up over time. > > > > > > > > > > > > Link: https://syzkaller.appspot.com/bug?extid=279432d30d825e63ba00 > > > > > > > > > > > > Cc: > > > > > > Reported-by: syzbot+adc3cb32385586bec859@syzkaller.appspotmail.com > > > > > > Signed-off-by: Lee Jones > > > > > > --- > > > > > > drivers/vhost/vhost.c | 10 ++++++++++ > > > > > > 1 file changed, 10 insertions(+) > > > > > > > > > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > > > > > index 59edb5a1ffe28..ef7e371e3e649 100644 > > > > > > --- a/drivers/vhost/vhost.c > > > > > > +++ b/drivers/vhost/vhost.c > > > > > > @@ -693,6 +693,15 @@ void vhost_dev_cleanup(struct vhost_dev *dev) > > > > > > int i; > > > > > > > > > > > > for (i = 0; i < dev->nvqs; ++i) { > > > > > > + /* No workers should run here by design. However, races have > > > > > > + * previously occurred where drivers have been unable to flush > > > > > > + * all work properly prior to clean-up. Without a successful > > > > > > + * flush the guest will malfunction, but avoiding host memory > > > > > > + * corruption in those cases does seem preferable. > > > > > > + */ > > > > > > + WARN_ON(mutex_is_locked(&dev->vqs[i]->mutex)); > > > > > > > > > > So you are trading one syzbot triggered issue for another one in the > > > > > future? :) > > > > > > > > > > If this ever can happen, handle it, but don't log it with a WARN_ON() as > > > > > that will trigger the panic-on-warn boxes, as well as syzbot. Unless > > > > > you want that to happen? > > > > > > > > No, Syzbot doesn't report warnings, only BUGs and memory corruption. > > > > > > Has it changed? Last I looked, it did trigger on WARN_* calls, which > > > has resulted in a huge number of kernel fixes because of that. > > > > Everything is customisable in syzkaller, so maybe there are specific > > builds which panic_on_warn enabled, but none that I'm involved with > > do. > > Many systems run with panic-on-warn (i.e. the cloud), as they want to > drop a box and restart it if anything goes wrong. > > That's why syzbot reports on WARN_* calls. They should never be > reachable by userspace actions. > > > Here follows a topical example. The report above in the Link: tag > > comes with a crashlog [0]. In there you can see the WARN() at the > > bottom of vhost_dev_cleanup() trigger many times due to a populated > > (non-flushed) worker list, before finally tripping the BUG() which > > triggers the report: > > > > [0] https://syzkaller.appspot.com/text?tag=CrashLog&x=16a61fce700000 > > Ok, so both happens here. But don't add a warning for something that > can't happen. Just handle it and move on. It looks like you are > handling it in this code, so please drop the WARN_ON(). Happy to oblige. Let's give Micheal a chance to speak, then I'll fix-up if he agrees. -- Lee Jones [李琼斯] Principal Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog