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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B740C433F5 for ; Wed, 3 Nov 2021 00:12:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7576960EDF for ; Wed, 3 Nov 2021 00:12:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233205AbhKCAPO (ORCPT ); Tue, 2 Nov 2021 20:15:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233194AbhKCAPN (ORCPT ); Tue, 2 Nov 2021 20:15:13 -0400 Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D169C061714 for ; Tue, 2 Nov 2021 17:12:38 -0700 (PDT) Received: by mail-il1-x136.google.com with SMTP id w15so835565ill.2 for ; Tue, 02 Nov 2021 17:12:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=1hFdIa5+UMPz4ryPHs3ofaiooiYhjKx88rmchvIn5NY=; b=gLfoJHd6ZKlzlQhbePQy2aggmQknUF8BWz65ttk38CoFAqmVayRCvKORjOJCI2iCLA HlpNX5x1DH2gk4M0muenjcV9BlGiLmYKWAQIQRKddJSE4yGxk9jiEiTIOs/U9IVYDX6J K9JMyXZBoaR6gCjYikPXnz5PYkLuXE1ilj0RtejIyCndyCwqiU2divrDhP4xR2Dsfhq3 9TNZINabHz+E/gvPNo1dNKIf92uVNzHMdVOLFHgjK4QU+PMkYZjVKGHS4x8Z9TnfbYiH H8741WpUobi3T8CFLP6PsQUNNMj+Y7HkO7MFVVfx4uQjUyIo1UqVmTzrmiRwrlHUduVv hd6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=1hFdIa5+UMPz4ryPHs3ofaiooiYhjKx88rmchvIn5NY=; b=A6icSGrG4g/OXESoW6uXlsm1jsbYXrsqBq+5670MY6O/LqVoMOYZsJo0rS98edFAhR eMU4kbxlIOxJxUg22Be5o9BfLrDvkp/d3BGQU+S0yLFqX6k1+PiYwXpi82a6DivGxfUh rzfwtHl7Jx2OBnEfXyOCGd5BOLLmQIszyioRN7B2pLn+sDZ3fURNFJVJzuYSfpC7mqbg 6/nSJtrQsgVEoMuS1o5CIebbHdmV+6cL5cqPvYC9ZaiObtEp8c53fgjhLocK45IUDQ2Y /J7hPIFkoKgjVhBW3Scz8dTxKP6d8BLEoZz3ulUmD1RLSa0VPnx8/7hV4eY4+SinYWQg C5fg== X-Gm-Message-State: AOAM532XbKSof//mYcrR9gg5r5eTj0Eg+KB6UYpje9I/VY9qHBUYuJn2 LsJnp2fG5MUDbymrfk2niyeJQHDk8gPzY9XHpc5dJQ== X-Google-Smtp-Source: ABdhPJyWD/JegcYFIIcy6BVOaSs6qyyeXkZkN5Cqniw7bm4x87PzruFAJR2UPC6iPqTJYKGsDlgM11UKmwiqgW0e39Q= X-Received: by 2002:a92:7f0e:: with SMTP id a14mr26683165ild.215.1635898357612; Tue, 02 Nov 2021 17:12:37 -0700 (PDT) MIME-Version: 1.0 References: <20210930085932.1.I8043d61cc238e0168e2f4ca5f4783223434aa587@changeid> <17d63b06-d1bd-85ab-92d3-71fa236b9493@suse.de> In-Reply-To: <17d63b06-d1bd-85ab-92d3-71fa236b9493@suse.de> From: "Anand K. Mistry" Date: Wed, 3 Nov 2021 11:12:25 +1100 Message-ID: Subject: Re: [PATCH] drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap To: Thomas Zimmermann Cc: dri-devel@lists.freedesktop.org, nartemiev@google.com, Daniel Vetter , David Airlie , Maarten Lankhorst , Maxime Ripard , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Any movement on merging this patch? Not urgent on my end (we have this patch in our tree), but I think other amd users might run into this UAF. On Thu, 30 Sept 2021 at 17:21, Thomas Zimmermann wrot= e: > > Hi > > Am 30.09.21 um 01:00 schrieb Anand K Mistry: > > drm_gem_ttm_mmap() drops a reference to the gem object on success. If > > the gem object's refcount =3D=3D 1 on entry to drm_gem_prime_mmap(), th= at > > drop will free the gem object, and the subsequent drm_gem_object_get() > > will be a UAF. Fix by grabbing a reference before calling the mmap > > helper. > > > > This issue was forseen when the reference dropping was adding in > > commit 9786b65bc61ac ("drm/ttm: fix mmap refcounting"): > > "For that to work properly the drm_gem_object_get() call in > > drm_gem_ttm_mmap() must be moved so it happens before calling > > obj->funcs->mmap(), otherwise the gem refcount would go down > > to zero." > > > > Signed-off-by: Anand K Mistry > > Acked-by: Thomas Zimmermann > > This looks fine to me, but it affects many drivers. Let's maybe wait a > bit if more reviews come it. > > Best regards > Thomas > > > --- > > > > drivers/gpu/drm/drm_prime.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > > index 2a54f86856af..e1854fd24bb0 100644 > > --- a/drivers/gpu/drm/drm_prime.c > > +++ b/drivers/gpu/drm/drm_prime.c > > @@ -719,11 +719,13 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj= , struct vm_area_struct *vma) > > if (obj->funcs && obj->funcs->mmap) { > > vma->vm_ops =3D obj->funcs->vm_ops; > > > > + drm_gem_object_get(obj); > > ret =3D obj->funcs->mmap(obj, vma); > > - if (ret) > > + if (ret) { > > + drm_gem_object_put(obj); > > return ret; > > + } > > vma->vm_private_data =3D obj; > > - drm_gem_object_get(obj); > > return 0; > > } > > > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany > (HRB 36809, AG N=C3=BCrnberg) > Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer --=20 Anand K. Mistry Software Engineer Google Australia 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2501EC433EF for ; Wed, 3 Nov 2021 00:12:41 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E1F1460E05 for ; Wed, 3 Nov 2021 00:12:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E1F1460E05 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E9D1D6E0E6; Wed, 3 Nov 2021 00:12:39 +0000 (UTC) Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) by gabe.freedesktop.org (Postfix) with ESMTPS id 81F536E0E6 for ; Wed, 3 Nov 2021 00:12:38 +0000 (UTC) Received: by mail-il1-x136.google.com with SMTP id i9so801645ilu.8 for ; Tue, 02 Nov 2021 17:12:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=1hFdIa5+UMPz4ryPHs3ofaiooiYhjKx88rmchvIn5NY=; b=gLfoJHd6ZKlzlQhbePQy2aggmQknUF8BWz65ttk38CoFAqmVayRCvKORjOJCI2iCLA HlpNX5x1DH2gk4M0muenjcV9BlGiLmYKWAQIQRKddJSE4yGxk9jiEiTIOs/U9IVYDX6J K9JMyXZBoaR6gCjYikPXnz5PYkLuXE1ilj0RtejIyCndyCwqiU2divrDhP4xR2Dsfhq3 9TNZINabHz+E/gvPNo1dNKIf92uVNzHMdVOLFHgjK4QU+PMkYZjVKGHS4x8Z9TnfbYiH H8741WpUobi3T8CFLP6PsQUNNMj+Y7HkO7MFVVfx4uQjUyIo1UqVmTzrmiRwrlHUduVv hd6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=1hFdIa5+UMPz4ryPHs3ofaiooiYhjKx88rmchvIn5NY=; b=7RAYK2Io5tQvZDobQ3PgSdLj9DRUUMyze4MY7xuZGaYwtB2+ScPqosCR+hlapWbiAo iJp4oRnHoULs0g0mARifImHEpAk8QsvMftkGA+QmrE9JERQ9qvdPRJsX4KOhWjp3ME2v B5y+AoVayM49UOqeKUXzTv3DvCvZDrzdFGRNfJ3BKLpaNlgozkAq8RiR93jgB7PjYdIj ReHW1vxK7txBLu1nshdWBcn0r9XGP1bTnr+ntAiZQ21HYTfWVAzJ6xhXuG3POhK6RPXO TekQnMNsdohrMbTSLQrpYbgU1cvMd/AhY1J+bwEEkP3MtBvxd1XuXdvEOFzMcBxBrA2p gNVw== X-Gm-Message-State: AOAM530B5TzTm5rDwL7k3yHVET31H5qwFF8x2M5z3+88yzhzQZ0klNtd WP1DqX0HPa9mxGLid6al6Q1BdMex9NajAbu0jksDAA== X-Google-Smtp-Source: ABdhPJyWD/JegcYFIIcy6BVOaSs6qyyeXkZkN5Cqniw7bm4x87PzruFAJR2UPC6iPqTJYKGsDlgM11UKmwiqgW0e39Q= X-Received: by 2002:a92:7f0e:: with SMTP id a14mr26683165ild.215.1635898357612; Tue, 02 Nov 2021 17:12:37 -0700 (PDT) MIME-Version: 1.0 References: <20210930085932.1.I8043d61cc238e0168e2f4ca5f4783223434aa587@changeid> <17d63b06-d1bd-85ab-92d3-71fa236b9493@suse.de> In-Reply-To: <17d63b06-d1bd-85ab-92d3-71fa236b9493@suse.de> From: "Anand K. Mistry" Date: Wed, 3 Nov 2021 11:12:25 +1100 Message-ID: Subject: Re: [PATCH] drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap To: Thomas Zimmermann Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Airlie , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, nartemiev@google.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Any movement on merging this patch? Not urgent on my end (we have this patch in our tree), but I think other amd users might run into this UAF. On Thu, 30 Sept 2021 at 17:21, Thomas Zimmermann wrot= e: > > Hi > > Am 30.09.21 um 01:00 schrieb Anand K Mistry: > > drm_gem_ttm_mmap() drops a reference to the gem object on success. If > > the gem object's refcount =3D=3D 1 on entry to drm_gem_prime_mmap(), th= at > > drop will free the gem object, and the subsequent drm_gem_object_get() > > will be a UAF. Fix by grabbing a reference before calling the mmap > > helper. > > > > This issue was forseen when the reference dropping was adding in > > commit 9786b65bc61ac ("drm/ttm: fix mmap refcounting"): > > "For that to work properly the drm_gem_object_get() call in > > drm_gem_ttm_mmap() must be moved so it happens before calling > > obj->funcs->mmap(), otherwise the gem refcount would go down > > to zero." > > > > Signed-off-by: Anand K Mistry > > Acked-by: Thomas Zimmermann > > This looks fine to me, but it affects many drivers. Let's maybe wait a > bit if more reviews come it. > > Best regards > Thomas > > > --- > > > > drivers/gpu/drm/drm_prime.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > > index 2a54f86856af..e1854fd24bb0 100644 > > --- a/drivers/gpu/drm/drm_prime.c > > +++ b/drivers/gpu/drm/drm_prime.c > > @@ -719,11 +719,13 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj= , struct vm_area_struct *vma) > > if (obj->funcs && obj->funcs->mmap) { > > vma->vm_ops =3D obj->funcs->vm_ops; > > > > + drm_gem_object_get(obj); > > ret =3D obj->funcs->mmap(obj, vma); > > - if (ret) > > + if (ret) { > > + drm_gem_object_put(obj); > > return ret; > > + } > > vma->vm_private_data =3D obj; > > - drm_gem_object_get(obj); > > return 0; > > } > > > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany > (HRB 36809, AG N=C3=BCrnberg) > Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer --=20 Anand K. Mistry Software Engineer Google Australia