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 5E4E5C433F5 for ; Tue, 23 Nov 2021 11:51:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234482AbhKWLyO (ORCPT ); Tue, 23 Nov 2021 06:54:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:41302 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235530AbhKWLyN (ORCPT ); Tue, 23 Nov 2021 06:54:13 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5843C60FED; Tue, 23 Nov 2021 11:51:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637668265; bh=2c2fYaPYBCvvqq67k+FdRCCqw1iXQX1D4CKTotC3d20=; h=Subject:To:Cc:From:Date:From; b=cN9sgcVM989Wrx73Q85eeCdee7tya9BOyauA66HqGpzL45m0ZLSZ0XeamCNQ137qa sv+GGcmWEPtvFNo7zZXDzSOk2Bcj2amA6BeyBnfcJpDKk3mAB2yLdazEwPZi4L6c6x ++HDB2IXZ8FSfaKjdQnXECFHFPZl9cfrx2iQCwmg= Subject: FAILED: patch "[PATCH] drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap" failed to apply to 5.10-stable tree To: amistry@google.com, airlied@linux.ie, daniel.vetter@ffwll.ch, daniel@ffwll.ch, kraxel@redhat.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, stable@vger.kernel.org, tzimmermann@suse.de Cc: From: Date: Tue, 23 Nov 2021 12:51:03 +0100 Message-ID: <163766826320226@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 8244a3bc27b3efd057da154b8d7e414670d5044f Mon Sep 17 00:00:00 2001 From: Anand K Mistry Date: Thu, 30 Sep 2021 09:00:07 +1000 Subject: [PATCH] drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap 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 diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index deb23dbec8b5..d6c7f4f9a7a2 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 = 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; }