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| author | Rob Clark | 2016-08-22 21:28:38 +0200 |
|---|---|---|
| committer | Rob Clark | 2016-08-28 18:49:39 +0200 |
| commit | d78d383ab354b0b9e1d23404ae0d9fbdeb9aa035 (patch) | |
| tree | aee4580ca0766d3be40c2b574dd7816aabc3d080 /drivers/gpu/drm | |
| parent | drm/msm: fix use of copy_from_user() while holding spinlock (diff) | |
| download | kernel-qcow2-linux-d78d383ab354b0b9e1d23404ae0d9fbdeb9aa035.tar.gz kernel-qcow2-linux-d78d383ab354b0b9e1d23404ae0d9fbdeb9aa035.tar.xz kernel-qcow2-linux-d78d383ab354b0b9e1d23404ae0d9fbdeb9aa035.zip | |
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 <robdclark@gmail.com>
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/msm/msm_drv.h | 6 | ||||
| -rw-r--r-- | drivers/gpu/drm/msm/msm_gem.c | 9 | ||||
| -rw-r--r-- | drivers/gpu/drm/msm/msm_gem_submit.c | 3 |
3 files changed, 18 insertions, 0 deletions
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h index b4bc7f1ef717..d0da52f2a806 100644 --- a/drivers/gpu/drm/msm/msm_drv.h +++ b/drivers/gpu/drm/msm/msm_drv.h @@ -157,6 +157,12 @@ struct msm_drm_private { struct shrinker shrinker; struct msm_vblank_ctrl vblank_ctrl; + + /* task holding struct_mutex.. currently only used in submit path + * to detect and reject faults from copy_from_user() for submit + * ioctl. + */ + struct task_struct *struct_mutex_task; }; struct msm_format { diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index 6cd4af443139..85f3047e05ae 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 */ diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c index 408da409a216..880d6a9af7c8 100644 --- a/drivers/gpu/drm/msm/msm_gem_submit.c +++ b/drivers/gpu/drm/msm/msm_gem_submit.c @@ -394,6 +394,8 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, if (ret) return ret; + priv->struct_mutex_task = current; + submit = submit_create(dev, gpu, args->nr_bos, args->nr_cmds); if (!submit) { ret = -ENOMEM; @@ -485,6 +487,7 @@ out: if (ret) msm_gem_submit_free(submit); out_unlock: + priv->struct_mutex_task = NULL; mutex_unlock(&dev->struct_mutex); return ret; } |