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 69EB1CCA47C for ; Wed, 29 Jun 2022 04:53:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230492AbiF2ExN (ORCPT ); Wed, 29 Jun 2022 00:53:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229475AbiF2ExL (ORCPT ); Wed, 29 Jun 2022 00:53:11 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7B29F3A; Tue, 28 Jun 2022 21:53:07 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id e63so14202776pgc.5; Tue, 28 Jun 2022 21:53:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=references:user-agent:from:to:cc:subject:date:in-reply-to :message-id:mime-version; bh=vvrW+kUlTZ7MKpOPos9PlIMBtA7/T3veu3b/qNQ3HBk=; b=RWls3DRvSuIvp4MMFexG8NTzv3f1yWJIbObXr8wAJtU1b77K3wjS3hgzGiIV9baW5W g0jeNMYYxJ9WUnguMI0eghGrDXzZiJ2NkOdu5oHzaxhR6TfDkHu/lejMNdAmg9ICpPYM mmxwiGbUbFKadjN9UsyUopgydT5mMlfE2aMZMbghSYeCvnwOkXcj2u92diZ2bgvvS5qr /WNZQrj5JgLoB9vvsr0fQO5Cgc6ipOZ2xmg5fS/GMT0GrSPh4yHjHocFnetz1bEmRTIC ixEjpBMmmmQahyDb+kutGg2JVBqLkKbyZYYtsW1YTR7hcx84OpvCevyaH03iM+ZAApe7 PUqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:references:user-agent:from:to:cc:subject:date :in-reply-to:message-id:mime-version; bh=vvrW+kUlTZ7MKpOPos9PlIMBtA7/T3veu3b/qNQ3HBk=; b=x5Vpt6m2Z+olqKQ6f8awRBhaMnGRgJsMoFICNb3mQClN6OqoACNcZDa8/sgnWQgvFo mOu7cyPxxbPbFfP4FEJTNBr+BWTZV8jX52//JAWUq48OVOCh3RHjy6qvx05D0K5J1WiQ kIYZt0WN0+onxffk6dlD3rIIptnHi+5i4NJa5HG+YnrieBz4E+fGJbtO4LjD0AI8rnS5 /2naKZU2GpI3+Jd5KxlV8sbrBcG1C1o+nTf9g4eIZ7CrTV2E7W65m80jPl0dkYff9KmM EuI5jGBk0Ngr/Ne+0VUTtQC987dvB6RezD+rnKXHG4D3y23gYYsGKCt2af8jhdZwl7KI BJAQ== X-Gm-Message-State: AJIora/jPIuGbAnDtRnFN9ZhWLOoyy0AUNIz9nuGh94Gzj4Rn+Kv58Jt 1dZxzgpJrXVj6dy7vdhlKeTwhGbI3uX5Ew== X-Google-Smtp-Source: AGRyM1tnQGZi67BTH5gEF2rN33/J4Y2Hvf2lwTTX4fq//ZWPUQYRzpCWWL/0D6hWTbaGZsbsk0j0ag== X-Received: by 2002:a63:8b43:0:b0:40d:1da6:948e with SMTP id j64-20020a638b43000000b0040d1da6948emr1372257pge.355.1656478386887; Tue, 28 Jun 2022 21:53:06 -0700 (PDT) Received: from MBP ([39.170.101.209]) by smtp.gmail.com with ESMTPSA id ip11-20020a17090b314b00b001ec84b0f199sm4990001pjb.1.2022.06.28.21.53.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jun 2022 21:53:06 -0700 (PDT) References: <20220628152429.286-1-schspa@gmail.com> <20220628095013.266d4a40.alex.williamson@redhat.com> <87ilokbx12.fsf@redhat.com> User-agent: mu4e 1.6.10; emacs 27.2 From: Schspa Shi To: Cornelia Huck Cc: Alex Williamson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] vfio: Clear the caps->buf to NULL after free Date: Wed, 29 Jun 2022 12:51:51 +0800 In-reply-to: <87ilokbx12.fsf@redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; format=flowed Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Cornelia Huck writes: > On Tue, Jun 28 2022, Alex Williamson > wrote: > >> 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. > > I like that better. With that, > > Reviewed-by: Cornelia Huck > I have send a V3 patch for this comment change, please review it. >> >> 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); >>> } -- BRs Schspa Shi