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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 471E9C433F5 for ; Tue, 23 Nov 2021 11:56:37 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 311826E057; Tue, 23 Nov 2021 11:56:36 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by gabe.freedesktop.org (Postfix) with ESMTPS id F000F6E057 for ; Tue, 23 Nov 2021 11:56:34 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 5A39560F42; Tue, 23 Nov 2021 11:56:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637668594; bh=JfElw6S/UmWCIqOZl7RklFinwJGA9nBHybOBRjZ81TI=; h=Subject:To:Cc:From:Date:From; b=UbCGmnxalk/QWbyHdNae+ERalyhGrDczdxF39Q+gYSiRgla0Gic1nftJnUdVaW3qm P42fHsA9haQROtUHdlTpbqe9sIdwt3kZK88Y/IgHu3klgFaeo/Nh/QZaAV9S82WOAG vF0PzYe+AQEWCANcCxqLI6UBCNM7whmHQm59HQqg= Subject: Patch "drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap" has been added to the 5.15-stable tree To: airlied@linux.ie, amistry@google.com, daniel.vetter@ffwll.ch, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, gregkh@linuxfoundation.org, kraxel@redhat.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de From: Date: Tue, 23 Nov 2021 12:56:05 +0100 Message-ID: <1637668565800@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore 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: stable-commits@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This is a note to let you know that I've just added the patch titled drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-prime-fix-use-after-free-in-mmap-with-drm_gem_ttm_mmap.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >From 8244a3bc27b3efd057da154b8d7e414670d5044f Mon Sep 17 00:00:00 2001 From: Anand K Mistry Date: Thu, 30 Sep 2021 09:00:07 +1000 Subject: drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap From: Anand K Mistry commit 8244a3bc27b3efd057da154b8d7e414670d5044f upstream. drm_gem_ttm_mmap() drops a reference to the gem object on success. If the gem object's refcount == 1 on entry to drm_gem_prime_mmap(), that 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 Fixes: 9786b65bc61a ("drm/ttm: fix mmap refcounting") Cc: Gerd Hoffmann Cc: Daniel Vetter Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Daniel Vetter Cc: dri-devel@lists.freedesktop.org Cc: # v5.5+ Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20210930085932.1.I8043d61cc238e0168e2f4ca5f4783223434aa587@changeid Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_prime.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- 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_ob if (obj->funcs && obj->funcs->mmap) { vma->vm_ops = obj->funcs->vm_ops; + drm_gem_object_get(obj); ret = obj->funcs->mmap(obj, vma); - if (ret) + if (ret) { + drm_gem_object_put(obj); return ret; + } vma->vm_private_data = obj; - drm_gem_object_get(obj); return 0; } Patches currently in stable-queue which might be from amistry@google.com are queue-5.15/drm-prime-fix-use-after-free-in-mmap-with-drm_gem_ttm_mmap.patch