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 A929CC0015E for ; Tue, 1 Aug 2023 20:27:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231899AbjHAU1h (ORCPT ); Tue, 1 Aug 2023 16:27:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229724AbjHAU1e (ORCPT ); Tue, 1 Aug 2023 16:27:34 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF81E2683 for ; Tue, 1 Aug 2023 13:26:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1690921605; 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: in-reply-to:in-reply-to:references:references; bh=Wy2TkA8uXc4KqWHCSUGw2dDqfqA9SqU7ECQFvC91hnU=; b=cH4PSjoSw7OFn3ihTRPkTVB9wQjjQztC8DeN8IMQtTg7zuU4jE+al2HnR0HfQ0YxV4Sof8 C4+1pvsc2+JOUCiSSPVI8pXmHKQswOpbB4RBhnBNIzsLi7IgF8Y4884QV33lDLmbOhf2vp Z3H6TTZtv+tqnuWa/DBHW3ywfWQnq+E= Received: from mail-il1-f200.google.com (mail-il1-f200.google.com [209.85.166.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-457-Utr-QiHnNuWzlcHMCTsJrQ-1; Tue, 01 Aug 2023 16:26:44 -0400 X-MC-Unique: Utr-QiHnNuWzlcHMCTsJrQ-1 Received: by mail-il1-f200.google.com with SMTP id e9e14a558f8ab-34908ea9bf8so34853865ab.0 for ; Tue, 01 Aug 2023 13:26:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690921604; x=1691526404; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Wy2TkA8uXc4KqWHCSUGw2dDqfqA9SqU7ECQFvC91hnU=; b=Xl+Fm936mD747RYg0du6GUJ14PT/OJKCGbNBhT1cel8MW8nJnPwH5ArRprnnDvTb0p /SxoQW+yyJMRjK5TZ2FxGqOFXcJCts8uI+qJUFhRY4cARFxcVmzEx1CLwhSZfdAoHFfV zBX2zhirWdGYWqSiWZ9yuGCQDHVj5pu344HXLTsdDfCRiH8lSHLBhDrTRLjdW09fH5Ag tbbftmGaId/iguTtL+z/zIyUbLtKsRz8I1iLXYlwWRyXfaJrnlggb/ZmFiuZPRtemH9H fhf7UVhNtbVR3NJWi0fs3JCrQ4tY5W4PUvLx5rbKY/8FwEcfgBbjcrQ9+Wqs8s3GtkTT H4mw== X-Gm-Message-State: ABy/qLY1JGhYXGd9IertkPVnV8XaALLx8PktifZBF5jh5mWBHXNpiPuF KwelYb7y2qKeI4vSSgbFXzy8+RjhtJiKcjAShgmU6N4fou6VFxcnykTwnU4Vd1nSGlMBiDlqIIb dH+fUZjCCqJbXmRQd4ziI32rx X-Received: by 2002:a05:6e02:1142:b0:348:b114:a3d2 with SMTP id o2-20020a056e02114200b00348b114a3d2mr10362596ill.21.1690921604041; Tue, 01 Aug 2023 13:26:44 -0700 (PDT) X-Google-Smtp-Source: APBJJlEbGknYdks2X0/d/P9ZjLKRglWMfz6zhjFdkrvnM7ln7ilY6KAPsrDg/JLdp7L+95yKWi2IeA== X-Received: by 2002:a05:6e02:1142:b0:348:b114:a3d2 with SMTP id o2-20020a056e02114200b00348b114a3d2mr10362588ill.21.1690921603816; Tue, 01 Aug 2023 13:26:43 -0700 (PDT) Received: from redhat.com ([38.15.60.12]) by smtp.gmail.com with ESMTPSA id gs14-20020a0566382d8e00b0042b61a5087csm3838753jab.132.2023.08.01.13.26.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Aug 2023 13:26:43 -0700 (PDT) Date: Tue, 1 Aug 2023 14:26:42 -0600 From: Alex Williamson To: Like Xu Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: eventfd: fix NULL deref irqbypass producer Message-ID: <20230801142642.1f73ca45.alex.williamson@redhat.com> In-Reply-To: <20230801085408.69597-1-likexu@tencent.com> References: <20230801085408.69597-1-likexu@tencent.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.35; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 1 Aug 2023 16:54:08 +0800 Like Xu wrote: > From: Like Xu > > Adding guard logic to make irq_bypass_register/unregister_producer() > looks for the producer entry based on producer pointer itself instead > of pure token matching. > > As was attempted commit 4f3dbdf47e15 ("KVM: eventfd: fix NULL deref > irqbypass consumer"), two different producers may occasionally have two > identical eventfd's. In this case, the later producer may unregister > the previous one after the registration fails (since they share the same > token), then NULL deref incurres in the path of deleting producer from > the producers list. > > Registration should also fail if a registered producer changes its > token and registers again via the same producer pointer. > > Cc: Alex Williamson > Signed-off-by: Like Xu > --- > virt/lib/irqbypass.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) Reviewed-by: Alex Williamson > > diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c > index 28fda42e471b..e0aabbbf27ec 100644 > --- a/virt/lib/irqbypass.c > +++ b/virt/lib/irqbypass.c > @@ -98,7 +98,7 @@ int irq_bypass_register_producer(struct irq_bypass_producer *producer) > mutex_lock(&lock); > > list_for_each_entry(tmp, &producers, node) { > - if (tmp->token == producer->token) { > + if (tmp->token == producer->token || tmp == producer) { > ret = -EBUSY; > goto out_err; > } > @@ -148,7 +148,7 @@ void irq_bypass_unregister_producer(struct irq_bypass_producer *producer) > mutex_lock(&lock); > > list_for_each_entry(tmp, &producers, node) { > - if (tmp->token != producer->token) > + if (tmp != producer) > continue; > > list_for_each_entry(consumer, &consumers, node) { > > base-commit: 5a7591176c47cce363c1eed704241e5d1c42c5a6