Commit b8a9ac1a authored by Frank Rowand's avatar Frank Rowand Committed by Rob Herring
Browse files

of: of_node_get()/of_node_put() nodes held in phandle cache 



The phandle cache contains struct device_node pointers.  The refcount
of the pointers was not incremented while in the cache, allowing use
after free error after kfree() of the node.  Add the proper increment
and decrement of the use count.

Fixes: 0b3ce78e ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()")
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: default avatarFrank Rowand <frank.rowand@sony.com>
Signed-off-by: default avatarRob Herring <robh@kernel.org>
parent 24ad02c4

drivers/of/base.c

+46 −24
Original line number Diff line number Diff line
@@ -123,9 +123,6 @@ int __weak of_node_to_nid(struct device_node *np) 
}

#endif



static struct device_node **phandle_cache;

static u32 phandle_cache_mask;



/*

 * Assumptions behind phandle_cache implementation:

 *   - phandle property values are in a contiguous range of 1..n
@@ -134,6 +131,44 @@ static u32 phandle_cache_mask; 
 *   - the phandle lookup overhead reduction provided by the cache

 *     will likely be less

 */



static struct device_node **phandle_cache;

static u32 phandle_cache_mask;



/*

 * Caller must hold devtree_lock.

 */

static void __of_free_phandle_cache(void)

{

	u32 cache_entries = phandle_cache_mask + 1;

	u32 k;



	if (!phandle_cache)

		return;



	for (k = 0; k < cache_entries; k++)

		of_node_put(phandle_cache[k]);



	kfree(phandle_cache);

	phandle_cache = NULL;

}



int of_free_phandle_cache(void)

{

	unsigned long flags;



	raw_spin_lock_irqsave(&devtree_lock, flags);



	__of_free_phandle_cache();



	raw_spin_unlock_irqrestore(&devtree_lock, flags);



	return 0;

}

#if !defined(CONFIG_MODULES)

late_initcall_sync(of_free_phandle_cache);

#endif



void of_populate_phandle_cache(void)

{

	unsigned long flags;
@@ -143,8 +178,7 @@ void of_populate_phandle_cache(void) 


	raw_spin_lock_irqsave(&devtree_lock, flags);



	kfree(phandle_cache);

	phandle_cache = NULL;

	__of_free_phandle_cache();



	for_each_of_allnodes(np)

		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
@@ -162,29 +196,14 @@ void of_populate_phandle_cache(void) 
		goto out;



	for_each_of_allnodes(np)

		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)

		if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) {

			of_node_get(np);

			phandle_cache[np->phandle & phandle_cache_mask] = np;



out:

	raw_spin_unlock_irqrestore(&devtree_lock, flags);

		}



int of_free_phandle_cache(void)

{

	unsigned long flags;



	raw_spin_lock_irqsave(&devtree_lock, flags);



	kfree(phandle_cache);

	phandle_cache = NULL;



out:

	raw_spin_unlock_irqrestore(&devtree_lock, flags);



	return 0;

}

#if !defined(CONFIG_MODULES)

late_initcall_sync(of_free_phandle_cache);

#endif



void __init of_core_init(void)

{
@@ -1200,8 +1219,11 @@ struct device_node *of_find_node_by_phandle(phandle handle) 
	if (!np) {

		for_each_of_allnodes(np)

			if (np->phandle == handle) {

				if (phandle_cache)

				if (phandle_cache) {

					/* will put when removed from cache */

					of_node_get(np);

					phandle_cache[masked_handle] = np;

				}

				break;

			}

	}

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