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drm/i915/gem: Tighten checks and acquiring the mmap object

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Make sure we hold the rcu lock as we acquire the rcu protected reference
of the object when looking it up from the associated mmap vma.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1083
Fixes: cc662126b4 ("drm/i915: Introduce DRM_I915_GEM_MMAP_OFFSET")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200130143931.1906301-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2020-01-30 14:39:31 +00:00
parent 37b7617262
commit 280d14a69d
2 changed files with 21 additions and 30 deletions
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39
drivers/gpu/drm/i915/gem/i915_gem_mman.c
View File

@ -807,60 +807,43 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma)
struct drm_vma_offset_node *node;
struct drm_file *priv = filp->private_data;
struct drm_device *dev = priv->minor->dev;
struct drm_i915_gem_object *obj = NULL;
struct i915_mmap_offset *mmo = NULL;
struct drm_gem_object *obj = NULL;
struct file *anon;
if (drm_dev_is_unplugged(dev))
return -ENODEV;
rcu_read_lock();
drm_vma_offset_lock_lookup(dev->vma_offset_manager);
node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
vma->vm_pgoff,
vma_pages(vma));
if (likely(node)) {
mmo = container_of(node, struct i915_mmap_offset,
vma_node);
/*
* In our dependency chain, the drm_vma_offset_node
* depends on the validity of the mmo, which depends on
* the gem object. However the only reference we have
* at this point is the mmo (as the parent of the node).
* Try to check if the gem object was at least cleared.
*/
if (!mmo || !mmo->obj) {
drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
return -EINVAL;
}
if (node && drm_vma_node_is_allowed(node, priv)) {
/*
* Skip 0-refcnted objects as it is in the process of being
* destroyed and will be invalid when the vma manager lock
* is released.
*/
obj = &mmo->obj->base;
if (!kref_get_unless_zero(&obj->refcount))
obj = NULL;
mmo = container_of(node, struct i915_mmap_offset, vma_node);
obj = i915_gem_object_get_rcu(mmo->obj);
}
drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
rcu_read_unlock();
if (!obj)
return -EINVAL;
return node ? -EACCES : -EINVAL;
if (!drm_vma_node_is_allowed(node, priv)) {
drm_gem_object_put_unlocked(obj);
return -EACCES;
}
if (i915_gem_object_is_readonly(to_intel_bo(obj))) {
if (i915_gem_object_is_readonly(obj)) {
if (vma->vm_flags & VM_WRITE) {
drm_gem_object_put_unlocked(obj);
i915_gem_object_put(obj);
return -EINVAL;
}
vma->vm_flags &= ~VM_MAYWRITE;
}
anon = mmap_singleton(to_i915(obj->dev));
anon = mmap_singleton(to_i915(dev));
if (IS_ERR(anon)) {
drm_gem_object_put_unlocked(obj);
i915_gem_object_put(obj);
return PTR_ERR(anon);
}

12
drivers/gpu/drm/i915/gem/i915_gem_object.h
View File

@ -69,6 +69,15 @@ i915_gem_object_lookup_rcu(struct drm_file *file, u32 handle)
return idr_find(&file->object_idr, handle);
}
static inline struct drm_i915_gem_object *
i915_gem_object_get_rcu(struct drm_i915_gem_object *obj)
{
if (obj && !kref_get_unless_zero(&obj->base.refcount))
obj = NULL;
return obj;
}
static inline struct drm_i915_gem_object *
i915_gem_object_lookup(struct drm_file *file, u32 handle)
{
@ -76,8 +85,7 @@ i915_gem_object_lookup(struct drm_file *file, u32 handle)
rcu_read_lock();
obj = i915_gem_object_lookup_rcu(file, handle);
if (obj && !kref_get_unless_zero(&obj->base.refcount))
obj = NULL;
obj = i915_gem_object_get_rcu(obj);
rcu_read_unlock();
return obj;