From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: fix use-after-free in i915_drop_caches_set Date: Mon, 8 Sep 2014 09:54:34 +0200 Message-ID: <20140908075434.GS15520@phenom.ffwll.local> References: <1409936003-9341-1-git-send-email-michel.thierry@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-we0-f182.google.com (mail-we0-f182.google.com [74.125.82.182]) by gabe.freedesktop.org (Postfix) with ESMTP id C6B966E223 for ; Mon, 8 Sep 2014 00:54:08 -0700 (PDT) Received: by mail-we0-f182.google.com with SMTP id w62so14463261wes.13 for ; Mon, 08 Sep 2014 00:54:07 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1409936003-9341-1-git-send-email-michel.thierry@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Michel Thierry Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Fri, Sep 05, 2014 at 05:53:23PM +0100, Michel Thierry wrote: > With the new vma/ppgtt lifetime rules, the ppgtt (vm) could be removed > after i915_vma_unbind. > > Use list_for_each_entry_safe() to prevent this use-after-free. > > Found with gem_persistent_relocs and gem_evict_everything igt tests. > > Cc: Daniel Vetter > Signed-off-by: Michel Thierry I've merged Chris' version of this already, which additional also grabs a temporary refcount to make sure the bo doesn't disappear untimely. Which can happen if unbind ends up dropping the last ref when dropping the active reference. -Daniel > --- > drivers/gpu/drm/i915/i915_debugfs.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c > index dd736c0..4b05cd8 100644 > --- a/drivers/gpu/drm/i915/i915_debugfs.c > +++ b/drivers/gpu/drm/i915/i915_debugfs.c > @@ -3820,8 +3820,8 @@ i915_drop_caches_set(void *data, u64 val) > struct drm_device *dev = data; > struct drm_i915_private *dev_priv = dev->dev_private; > struct drm_i915_gem_object *obj, *next; > - struct i915_address_space *vm; > - struct i915_vma *vma, *x; > + struct i915_address_space *vm, *x; > + struct i915_vma *vma, *y; > int ret; > > DRM_DEBUG("Dropping caches: 0x%08llx\n", val); > @@ -3842,8 +3842,9 @@ i915_drop_caches_set(void *data, u64 val) > i915_gem_retire_requests(dev); > > if (val & DROP_BOUND) { > - list_for_each_entry(vm, &dev_priv->vm_list, global_link) { > - list_for_each_entry_safe(vma, x, &vm->inactive_list, > + list_for_each_entry_safe(vm, x, &dev_priv->vm_list, > + global_link) { > + list_for_each_entry_safe(vma, y, &vm->inactive_list, > mm_list) { > if (vma->pin_count) > continue; > -- > 2.0.3 > -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch