From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 301FE20D4E9 for ; Wed, 22 Oct 2025 05:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761111944; cv=none; b=M6/1OUfh5jFTBE0bAB0YQBxXExwATRr1p11GvKS1k0HFGwO5SPc/vKozcGhbZVrLquz1Vix/kLQfK28aX6Hnvh1tPr7R5kNGxTVpmNALK09wU9kjIEleNnUSqAnDcTEAn/dPzvL7pDiLQfHq3IyombfaF/YJsBgdywPJB2Tq8Sw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761111944; c=relaxed/simple; bh=OOEDwYf/WoldymVHE1bARmPBao5IcHvki7sxdMEqYj8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=snaCcgepi7p4RayMqqxMxhjKcSj8gjjnBO4QK9g8x4xC+0t9k9z+DSLk/s6QKBv+yqtYveXXdyZ3AwOjlBeI+Xzpeiq90zfyC3zE11mK0tBfw6nGSNqtoxPGsclO45YBfkTNbgtXTU3g/CSsgOtyj9eibM2I4WdknvtusGYcbSE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OY4d43Ge; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OY4d43Ge" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761111941; 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=+gdOCtyqfpPDKTOSjwLO+fIICNulbuVoEvWA7TNWh1Q=; b=OY4d43GeZy8RoHxJ98+KEGoz+NMxMwsdR92GCbAJVByzmDCfeiLyviRx/XZCGk6hQDaIKY vPyTcSEA3u1T6cgkHoKKNZfCMEsVQyfimzXVtfk15B+mwMLN3pMuqZYFHTEHGTl5GJRUJM 2oGnjSqL6K2vZFOrpAz6j5Mt6+eGM88= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-392-X_IDuKiSPxyQ5EPKpj1sWg-1; Wed, 22 Oct 2025 01:45:40 -0400 X-MC-Unique: X_IDuKiSPxyQ5EPKpj1sWg-1 X-Mimecast-MFC-AGG-ID: X_IDuKiSPxyQ5EPKpj1sWg_1761111939 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-471168953bdso4114295e9.1 for ; Tue, 21 Oct 2025 22:45:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761111939; x=1761716739; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+gdOCtyqfpPDKTOSjwLO+fIICNulbuVoEvWA7TNWh1Q=; b=OuqHt1hULNIK7tKgEqtyKUP8IyJUxsmqvoi28suLb7fDehgi/wcxb/pwdbqnyCe0Wo sG79uuwRPHHrgOwi2BMVdDwDV62gLestkPnQ4IINdfnrbpD1THquDileTErAzkVrfVVk xlBeKCGG/Ndm7PVPSioH6+0kfnYWx51HTee9LKB+FsCJ8xdNtxAUe2988PnxczqDrK17 5vO5yFYZ8KFMWbQ07LbBb21y3xcd8nupytX5vy83JXxkLr+3a1sGEWSplrVjS7WO7hDY yV/ooe3rBW1SdP+aIuuXqvSY0a7z1t9cxaKJHXEqePdN47AB+z0JjxoIYdBxSsUf9R9m 6EoQ== X-Forwarded-Encrypted: i=1; AJvYcCUp0wfolkOTn6qXsgB+bR4O3Udy7fxH3OFc4MhkTl07wA1mwxDSilM5DuqZACsDhOZaIP0e/lAUhZk5Cos=@vger.kernel.org X-Gm-Message-State: AOJu0Yz2/vXgPX0H71rBRbb6H7F85IqrbeuNdkun4NVUT2qOK9oinyGE 1QRoKWaTk+XLLSAdV1nCV4YewE+4XeBFJ0tIfWEB2T+pg2rnAoHr8K+zjrUHwIoD8UIAMN7TIJZ IXgKlDMpYeU06USS4eI7og3n8ZA4NX0O9Hr3mNvOff0pjiiN+UaIUJdXsefkv/f1Z1w== X-Gm-Gg: ASbGnctB9WFE1+HRrFsm/CkMX26eu7W1zKXeCsafWRhNawVIliQVISzy1FF455361BJ 1Tj0lriXmIb6mNEcM8IBthPAcdFX5rGOOQPKL0g5FdwA7Owwu5gsT1BP1+0K4f2zVxPi5sG39QS pHrSDSbZF8Of+OOsVvKJqqk06ONvysJrh+3FgsHbb07GZl1M+SPKrkvpveawhyBwNOo7ZkaMd6s 9nVXAvs2fNg+8IApCJSsy4nu08psMzSPNJ8b7RV15rgOKbvCAll7oGqR9+uSkD+ZemqY+cGHLwU JdNXHiGjmOCRE/s7LWtD3qtf01OD2ZmnfqpfoNoqS99fXPcvQG8D9nGN5420Dvb/kaQN X-Received: by 2002:a05:600c:6992:b0:471:5c0:94fc with SMTP id 5b1f17b1804b1-475c3fa355cmr13586805e9.6.1761111939131; Tue, 21 Oct 2025 22:45:39 -0700 (PDT) X-Google-Smtp-Source: AGHT+IElHGkXoX3hCkc0GRrDbDcYpbH4YLBEG6cIW8mw2RcnC42OK12DSE/fMXDY2iXzD02ahYxuXQ== X-Received: by 2002:a05:600c:6992:b0:471:5c0:94fc with SMTP id 5b1f17b1804b1-475c3fa355cmr13586695e9.6.1761111938746; Tue, 21 Oct 2025 22:45:38 -0700 (PDT) Received: from redhat.com ([2a0d:6fc0:152d:b200:2a90:8f13:7c1e:f479]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47494ab11bbsm30712795e9.1.2025.10.21.22.45.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Oct 2025 22:45:38 -0700 (PDT) Date: Wed, 22 Oct 2025 01:45:35 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Cong Zhang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Paolo Bonzini , Stefan Hajnoczi , Jens Axboe , linux-arm-msm@vger.kernel.org, virtualization@lists.linux.dev, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, pavan.kondeti@oss.qualcomm.com Subject: Re: [PATCH] virtio_blk: NULL out vqs to avoid double free on failed resume Message-ID: <20251022014453-mutt-send-email-mst@kernel.org> References: <20251021-virtio_double_free-v1-1-4dd0cfd258f1@oss.qualcomm.com> <20251021085030-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Oct 22, 2025 at 12:19:19PM +0800, Jason Wang wrote: > On Tue, Oct 21, 2025 at 8:58 PM Michael S. Tsirkin wrote: > > > > On Tue, Oct 21, 2025 at 07:07:56PM +0800, Cong Zhang wrote: > > > The vblk->vqs releases during freeze. If resume fails before vblk->vqs > > > is allocated, later freeze/remove may attempt to free vqs again. > > > Set vblk->vqs to NULL after freeing to avoid double free. > > > > > > Signed-off-by: Cong Zhang > > > --- > > > The patch fixes a double free issue that occurs in virtio_blk during > > > freeze/resume. > > > The issue is caused by: > > > 1. During the first freeze, vblk->vqs is freed but pointer is not set to > > > NULL. > > > 2. Virtio block device fails before vblk->vqs is allocated during resume. > > > 3. During the next freeze, vblk->vqs gets freed again, causing the > > > double free crash. > > > > this part I don't get. if restore fails, how can freeze be called > > again? > > For example, could it be triggered by the user? > > Thanks I don't know - were you able to trigger it? how? > > > > > --- > > > drivers/block/virtio_blk.c | 13 ++++++++++++- > > > 1 file changed, 12 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > > > index f061420dfb10c40b21765b173fab7046aa447506..746795066d7f56a01c9a9c0344d24f9fa06841eb 100644 > > > --- a/drivers/block/virtio_blk.c > > > +++ b/drivers/block/virtio_blk.c > > > @@ -1026,8 +1026,13 @@ static int init_vq(struct virtio_blk *vblk) > > > out: > > > kfree(vqs); > > > kfree(vqs_info); > > > - if (err) > > > + if (err) { > > > kfree(vblk->vqs); > > > + /* > > > + * Set to NULL to prevent freeing vqs again during freezing. > > > + */ > > > + vblk->vqs = NULL; > > > + } > > > return err; > > > } > > > > > > > > @@ -1598,6 +1603,12 @@ static int virtblk_freeze_priv(struct virtio_device *vdev) > > > > > > vdev->config->del_vqs(vdev); > > > kfree(vblk->vqs); > > > + /* > > > + * Set to NULL to prevent freeing vqs again after a failed vqs > > > + * allocation during resume. Note that kfree() already handles NULL > > > + * pointers safely. > > > + */ > > > + vblk->vqs = NULL; > > > > > > return 0; > > > } > > > > > > --- > > > base-commit: 8e2755d7779a95dd61d8997ebce33ff8b1efd3fb > > > change-id: 20250926-virtio_double_free-7ab880d82a17 > > > > > > Best regards, > > > -- > > > Cong Zhang > >