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Commit 534e5f84 authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

drm/radeon: use mmu_notifier_get/put for struct radeon_mn 

radeon is using a device global hash table to track what mmu_notifiers
have been registered on struct mm. This is better served with the new
get/put scheme instead.

radeon has a bug where it was not blocking notifier release() until all
the BO's had been invalidated. This could result in a use after free of
pages the BOs. This is tied into a second bug where radeon left the
notifiers running endlessly even once the interval tree became
empty. This could result in a use after free with module unload.

Both are fixed by changing the lifetime model, the BOs exist in the
interval tree with their natural lifetimes independent of the mm_struct
lifetime using the get/put scheme. The release runs synchronously and just
does invalidate_start across the entire interval tree to create the
required DMA fence.

Additions to the interval tree after release are already impossible as
only current->mm is used during the add.

Link: https://lore.kernel.org/r/20190806231548.25242-9-jgg@ziepe.ca


Acked-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@mellanox.com>
parent c7d8b782

drivers/gpu/drm/radeon/radeon.h

+0 −3
Original line number Diff line number Diff line
@@ -2451,9 +2451,6 @@ struct radeon_device { 
	/* tracking pinned memory */

	u64 vram_pin_size;

	u64 gart_pin_size;



	struct mutex	mn_lock;

	DECLARE_HASHTABLE(mn_hash, 7);

};



bool radeon_is_px(struct drm_device *dev);

drivers/gpu/drm/radeon/radeon_device.c

+0 −2
Original line number Diff line number Diff line
@@ -1325,8 +1325,6 @@ int radeon_device_init(struct radeon_device *rdev, 
	init_rwsem(&rdev->pm.mclk_lock);

	init_rwsem(&rdev->exclusive_lock);

	init_waitqueue_head(&rdev->irq.vblank_queue);

	mutex_init(&rdev->mn_lock);

	hash_init(rdev->mn_hash);

	r = radeon_gem_init(rdev);

	if (r)

		return r;

drivers/gpu/drm/radeon/radeon_drv.c

+2 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
#include <linux/module.h>

#include <linux/pm_runtime.h>

#include <linux/vga_switcheroo.h>

#include <linux/mmu_notifier.h>



#include <drm/drm_crtc_helper.h>

#include <drm/drm_drv.h>
@@ -624,6 +625,7 @@ static void __exit radeon_exit(void) 
{

	pci_unregister_driver(pdriver);

	radeon_unregister_atpx_handler();

	mmu_notifier_synchronize();

}



module_init(radeon_init);

drivers/gpu/drm/radeon/radeon_mn.c

+36 −121
Original line number Diff line number Diff line
@@ -37,17 +37,8 @@ 
#include "radeon.h"



struct radeon_mn {

	/* constant after initialisation */

	struct radeon_device	*rdev;

	struct mm_struct	*mm;

	struct mmu_notifier	mn;



	/* only used on destruction */

	struct work_struct	work;



	/* protected by rdev->mn_lock */

	struct hlist_node	node;



	/* objects protected by lock */

	struct mutex		lock;

	struct rb_root_cached	objects;
@@ -58,55 +49,6 @@ struct radeon_mn_node { 
	struct list_head		bos;

};



/**

 * radeon_mn_destroy - destroy the rmn

 *

 * @work: previously sheduled work item

 *

 * Lazy destroys the notifier from a work item

 */

static void radeon_mn_destroy(struct work_struct *work)

{

	struct radeon_mn *rmn = container_of(work, struct radeon_mn, work);

	struct radeon_device *rdev = rmn->rdev;

	struct radeon_mn_node *node, *next_node;

	struct radeon_bo *bo, *next_bo;



	mutex_lock(&rdev->mn_lock);

	mutex_lock(&rmn->lock);

	hash_del(&rmn->node);

	rbtree_postorder_for_each_entry_safe(node, next_node,

					     &rmn->objects.rb_root, it.rb) {



		interval_tree_remove(&node->it, &rmn->objects);

		list_for_each_entry_safe(bo, next_bo, &node->bos, mn_list) {

			bo->mn = NULL;

			list_del_init(&bo->mn_list);

		}

		kfree(node);

	}

	mutex_unlock(&rmn->lock);

	mutex_unlock(&rdev->mn_lock);

	mmu_notifier_unregister(&rmn->mn, rmn->mm);

	kfree(rmn);

}



/**

 * radeon_mn_release - callback to notify about mm destruction

 *

 * @mn: our notifier

 * @mn: the mm this callback is about

 *

 * Shedule a work item to lazy destroy our notifier.

 */

static void radeon_mn_release(struct mmu_notifier *mn,

			      struct mm_struct *mm)

{

	struct radeon_mn *rmn = container_of(mn, struct radeon_mn, mn);

	INIT_WORK(&rmn->work, radeon_mn_destroy);

	schedule_work(&rmn->work);

}



/**

 * radeon_mn_invalidate_range_start - callback to notify about mm change

 *
@@ -183,65 +125,44 @@ static int radeon_mn_invalidate_range_start(struct mmu_notifier *mn, 
	return ret;

}



static const struct mmu_notifier_ops radeon_mn_ops = {

	.release = radeon_mn_release,

	.invalidate_range_start = radeon_mn_invalidate_range_start,

static void radeon_mn_release(struct mmu_notifier *mn, struct mm_struct *mm)

{

	struct mmu_notifier_range range = {

		.mm = mm,

		.start = 0,

		.end = ULONG_MAX,

		.flags = 0,

		.event = MMU_NOTIFY_UNMAP,

	};



/**

 * radeon_mn_get - create notifier context

 *

 * @rdev: radeon device pointer

 *

 * Creates a notifier context for current->mm.

 */

static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev)

	radeon_mn_invalidate_range_start(mn, &range);

}



static struct mmu_notifier *radeon_mn_alloc_notifier(struct mm_struct *mm)

{

	struct mm_struct *mm = current->mm;

	struct radeon_mn *rmn;

	int r;



	if (down_write_killable(&mm->mmap_sem))

		return ERR_PTR(-EINTR);



	mutex_lock(&rdev->mn_lock);



	hash_for_each_possible(rdev->mn_hash, rmn, node, (unsigned long)mm)

		if (rmn->mm == mm)

			goto release_locks;



	rmn = kzalloc(sizeof(*rmn), GFP_KERNEL);

	if (!rmn) {

		rmn = ERR_PTR(-ENOMEM);

		goto release_locks;

	}

	if (!rmn)

		return ERR_PTR(-ENOMEM);



	rmn->rdev = rdev;

	rmn->mm = mm;

	rmn->mn.ops = &radeon_mn_ops;

	mutex_init(&rmn->lock);

	rmn->objects = RB_ROOT_CACHED;

	return &rmn->mn;

}



	r = __mmu_notifier_register(&rmn->mn, mm);

	if (r)

		goto free_rmn;



	hash_add(rdev->mn_hash, &rmn->node, (unsigned long)mm);



release_locks:

	mutex_unlock(&rdev->mn_lock);

	up_write(&mm->mmap_sem);



	return rmn;



free_rmn:

	mutex_unlock(&rdev->mn_lock);

	up_write(&mm->mmap_sem);

	kfree(rmn);



	return ERR_PTR(r);

static void radeon_mn_free_notifier(struct mmu_notifier *mn)

{

	kfree(container_of(mn, struct radeon_mn, mn));

}



static const struct mmu_notifier_ops radeon_mn_ops = {

	.release = radeon_mn_release,

	.invalidate_range_start = radeon_mn_invalidate_range_start,

	.alloc_notifier = radeon_mn_alloc_notifier,

	.free_notifier = radeon_mn_free_notifier,

};



/**

 * radeon_mn_register - register a BO for notifier updates

 *
@@ -254,15 +175,16 @@ static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev) 
int radeon_mn_register(struct radeon_bo *bo, unsigned long addr)

{

	unsigned long end = addr + radeon_bo_size(bo) - 1;

	struct radeon_device *rdev = bo->rdev;

	struct mmu_notifier *mn;

	struct radeon_mn *rmn;

	struct radeon_mn_node *node = NULL;

	struct list_head bos;

	struct interval_tree_node *it;



	rmn = radeon_mn_get(rdev);

	if (IS_ERR(rmn))

		return PTR_ERR(rmn);

	mn = mmu_notifier_get(&radeon_mn_ops, current->mm);

	if (IS_ERR(mn))

		return PTR_ERR(mn);

	rmn = container_of(mn, struct radeon_mn, mn);



	INIT_LIST_HEAD(&bos);
@@ -309,22 +231,13 @@ int radeon_mn_register(struct radeon_bo *bo, unsigned long addr) 
 */

void radeon_mn_unregister(struct radeon_bo *bo)

{

	struct radeon_device *rdev = bo->rdev;

	struct radeon_mn *rmn;

	struct radeon_mn *rmn = bo->mn;

	struct list_head *head;



	mutex_lock(&rdev->mn_lock);

	rmn = bo->mn;

	if (rmn == NULL) {

		mutex_unlock(&rdev->mn_lock);

		return;

	}



	mutex_lock(&rmn->lock);

	/* save the next list entry for later */

	head = bo->mn_list.next;



	bo->mn = NULL;

	list_del(&bo->mn_list);



	if (list_empty(head)) {
@@ -335,5 +248,7 @@ void radeon_mn_unregister(struct radeon_bo *bo) 
	}



	mutex_unlock(&rmn->lock);

	mutex_unlock(&rdev->mn_lock);



	mmu_notifier_put(&rmn->mn);

	bo->mn = NULL;

}