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Commit 3af20bdd authored by Daniel Rosenberg's avatar Daniel Rosenberg Committed by Greg Kroah-Hartman
Browse files

staging: android: ion: check for kref overflow 



This patch is against 4.9. It does not apply to master due to a large
rework of ion in 4.12 which removed the affected functions altogther.
4c23cbff073f3b9b ("staging: android: ion: Remove import interface")

Userspace can cause the kref to handles to increment
arbitrarily high. Ensure it does not overflow.

Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b8c0e154

drivers/staging/android/ion/ion.c

+14 −3
Original line number Original line Diff line number Diff line
@@ -15,6 +15,7 @@ 
 *

 *

 */

 */





#include <linux/atomic.h>

#include <linux/device.h>

#include <linux/device.h>

#include <linux/err.h>

#include <linux/err.h>

#include <linux/file.h>

#include <linux/file.h>
@@ -305,6 +306,16 @@ static void ion_handle_get(struct ion_handle *handle) 
	kref_get(&handle->ref);

	kref_get(&handle->ref);

}

}





/* Must hold the client lock */

static struct ion_handle *ion_handle_get_check_overflow(

					struct ion_handle *handle)

{

	if (atomic_read(&handle->ref.refcount) + 1 == 0)

		return ERR_PTR(-EOVERFLOW);

	ion_handle_get(handle);

	return handle;

}



int ion_handle_put_nolock(struct ion_handle *handle)

int ion_handle_put_nolock(struct ion_handle *handle)

{

{

	return kref_put(&handle->ref, ion_handle_destroy);

	return kref_put(&handle->ref, ion_handle_destroy);
@@ -347,9 +358,9 @@ struct ion_handle *ion_handle_get_by_id_nolock(struct ion_client *client, 




	handle = idr_find(&client->idr, id);

	handle = idr_find(&client->idr, id);

	if (handle)

	if (handle)

		ion_handle_get(handle);

		return ion_handle_get_check_overflow(handle);





	return handle ? handle : ERR_PTR(-EINVAL);

	return ERR_PTR(-EINVAL);

}

}





static bool ion_handle_validate(struct ion_client *client,

static bool ion_handle_validate(struct ion_client *client,
@@ -1110,7 +1121,7 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client, 
	/* if a handle exists for this buffer just take a reference to it */

	/* if a handle exists for this buffer just take a reference to it */

	handle = ion_handle_lookup(client, buffer);

	handle = ion_handle_lookup(client, buffer);

	if (!IS_ERR(handle)) {

	if (!IS_ERR(handle)) {

		ion_handle_get(handle);

		handle = ion_handle_get_check_overflow(handle);

		mutex_unlock(&client->lock);

		mutex_unlock(&client->lock);

		goto end;

		goto end;

	}

	}