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 E89A4C433EF for ; Tue, 28 Jun 2022 15:50:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347642AbiF1PuV (ORCPT ); Tue, 28 Jun 2022 11:50:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59710 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347161AbiF1PuU (ORCPT ); Tue, 28 Jun 2022 11:50:20 -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 ESMTP id 05FD8237FE for ; Tue, 28 Jun 2022 08:50:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1656431417; 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=DakxM/+KiFO/D3po2I8kW227ufqvmzL2vNaM+Nshp8A=; b=GPd8kAa3safcG/cbjKoqrOAKQ/XlXnFmn3V1JPyeqyw6JVSYhQthJ12mG//P3mJZh/Bl/B haREDhG7cWkrWB+XD1LIe4Zui+djXiNl05wDYqCW0GmQL44ealAmjmqrORjWrDRPIkbzN9 Tdp1d2ysZEAtbqx2tMxcMe2hnjqkCkw= Received: from mail-il1-f198.google.com (mail-il1-f198.google.com [209.85.166.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-421-KkZHI8BHNzWQDwMzg5Zc_A-1; Tue, 28 Jun 2022 11:50:15 -0400 X-MC-Unique: KkZHI8BHNzWQDwMzg5Zc_A-1 Received: by mail-il1-f198.google.com with SMTP id b11-20020a92340b000000b002d3dbbc7b15so7508704ila.5 for ; Tue, 28 Jun 2022 08:50:15 -0700 (PDT) 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:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=DakxM/+KiFO/D3po2I8kW227ufqvmzL2vNaM+Nshp8A=; b=x/v+Q3y6y6Z0KP2+34/0se9gy1jwfJeCVB6rS5yS+M2aMaxTuCijFn9R1iuzUQHlqT zZwQZD9hHBbOaX5w5CvBvWRCCluuqZuqtVdYMo67b67ZpPHv8gxNGTM3Am0ypl+un4B1 hE7WNe+blTWsn7rwBRDBA3/rOU8S+xnzIEaj+Zb3AagxmQrFBsqDMMVtqIUmMryIE2Ts FeQx806oeQ6elzVMvS8+BrZkkCAgUnJjsH3teh+HZkn8zjWaKca6pujm0AfcXMLEgTfn sMaMbsxytnL6+kRximE9HLYbl/+fCwsT6YZGhEg7NcySi760X279T7LzIzHpOQvvTUfM Xj9A== X-Gm-Message-State: AJIora8EQ7Nvu1fPRsbp58yRFYSN9tQ9erzsg89QxfpIb3/ULotVITg0 Al3F8tWPYavSbfkRp6VrhftGRtNOXQlhmKNb7a3sEO1m1P8u2O1csBaqWA2SOUOaPDGiJGsWoVp 8wWunLJcW5Sb4N+Ey9hrsyeyS X-Received: by 2002:a05:6e02:801:b0:2da:7df7:e7c3 with SMTP id u1-20020a056e02080100b002da7df7e7c3mr9657808ilm.105.1656431415121; Tue, 28 Jun 2022 08:50:15 -0700 (PDT) X-Google-Smtp-Source: AGRyM1sTVMbC8M0efZplHFG6sL7/SCrWa4uNmFX9wKMHlhrZRZ81Qtgx1LsCXyNRHQBr028dopIYBA== X-Received: by 2002:a05:6e02:801:b0:2da:7df7:e7c3 with SMTP id u1-20020a056e02080100b002da7df7e7c3mr9657799ilm.105.1656431414921; Tue, 28 Jun 2022 08:50:14 -0700 (PDT) Received: from redhat.com ([38.15.36.239]) by smtp.gmail.com with ESMTPSA id a14-20020a5d980e000000b006696754eef5sm6655206iol.13.2022.06.28.08.50.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jun 2022 08:50:14 -0700 (PDT) Date: Tue, 28 Jun 2022 09:50:13 -0600 From: Alex Williamson To: Schspa Shi Cc: cohuck@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] vfio: Clear the caps->buf to NULL after free Message-ID: <20220628095013.266d4a40.alex.williamson@redhat.com> In-Reply-To: <20220628152429.286-1-schspa@gmail.com> References: <20220628152429.286-1-schspa@gmail.com> Organization: Red Hat 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, 28 Jun 2022 23:24:29 +0800 Schspa Shi wrote: > API vfio_info_cap_add will free caps->buf, clear it to NULL after > free. Should this be something like: On buffer resize failure, vfio_info_cap_add() will free the buffer, report zero for the size, and return -ENOMEM. As additional hardening, also clear the buffer pointer to prevent any chance of a double free. Thanks, Alex > Signed-off-by: Schspa Shi > --- > drivers/vfio/vfio.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > index 61e71c1154be..a0fb93866f61 100644 > --- a/drivers/vfio/vfio.c > +++ b/drivers/vfio/vfio.c > @@ -1812,6 +1812,7 @@ struct vfio_info_cap_header *vfio_info_cap_add(struct vfio_info_cap *caps, > buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL); > if (!buf) { > kfree(caps->buf); > + caps->buf = NULL; > caps->size = 0; > return ERR_PTR(-ENOMEM); > }