From d78d383ab354b0b9e1d23404ae0d9fbdeb9aa035 Mon Sep 17 00:00:00 2001 From: Rob Clark Date: Mon, 22 Aug 2016 15:28:38 -0400 Subject: drm/msm: protect against faults from copy_from_user() in submit ioctl An evil userspace could try to cause deadlock by passing an unfaulted-in GEM bo as submit->bos (or submit->cmds) table. Which will trigger msm_gem_fault() while we already hold struct_mutex. See: https://github.com/freedreno/msmtest/blob/master/evilsubmittest.c Cc: stable@vger.kernel.org Signed-off-by: Rob Clark --- drivers/gpu/drm/msm/msm_gem.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'drivers/gpu/drm/msm/msm_gem.c') diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index 6cd4af4..85f3047 100644 --- a/drivers/gpu/drm/msm/msm_gem.c +++ b/drivers/gpu/drm/msm/msm_gem.c @@ -196,11 +196,20 @@ int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct drm_gem_object *obj = vma->vm_private_data; struct drm_device *dev = obj->dev; + struct msm_drm_private *priv = dev->dev_private; struct page **pages; unsigned long pfn; pgoff_t pgoff; int ret; + /* This should only happen if userspace tries to pass a mmap'd + * but unfaulted gem bo vaddr into submit ioctl, triggering + * a page fault while struct_mutex is already held. This is + * not a valid use-case so just bail. + */ + if (priv->struct_mutex_task == current) + return VM_FAULT_SIGBUS; + /* Make sure we don't parallel update on a fault, nor move or remove * something from beneath our feet */ -- cgit v1.1