1 files changed, 51 insertions, 26 deletions

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 374f840f31a4..4adb1138af09 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -15,6 +15,7 @@
  *
  */
 
+#include <linux/atomic.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/file.h>
@@ -387,6 +388,16 @@ static void ion_handle_get(struct ion_handle *handle)
 	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;
+}
+
 static int ion_handle_put_nolock(struct ion_handle *handle)
 {
 	int ret;
@@ -433,21 +444,9 @@ static struct ion_handle *ion_handle_get_by_id_nolock(struct ion_client *client,
 
 	handle = idr_find(&client->idr, id);
 	if (handle)
-		ion_handle_get(handle);
-
-	return handle ? handle : ERR_PTR(-EINVAL);
-}
-
-struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
-						int id)
-{
-	struct ion_handle *handle;
-
-	mutex_lock(&client->lock);
-	handle = ion_handle_get_by_id_nolock(client, id);
-	mutex_unlock(&client->lock);
+		return ion_handle_get_check_overflow(handle);
 
-	return handle;
+	return ERR_PTR(-EINVAL);
 }
 
 static bool ion_handle_validate(struct ion_client *client,
@@ -1127,24 +1126,28 @@ static struct dma_buf_ops dma_buf_ops = {
 	.kunmap = ion_dma_buf_kunmap,
 };
 
-struct dma_buf *ion_share_dma_buf(struct ion_client *client,
-						struct ion_handle *handle)
+static struct dma_buf *__ion_share_dma_buf(struct ion_client *client,
+					   struct ion_handle *handle,
+					   bool lock_client)
 {
 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 	struct ion_buffer *buffer;
 	struct dma_buf *dmabuf;
 	bool valid_handle;
 
-	mutex_lock(&client->lock);
+	if (lock_client)
+		mutex_lock(&client->lock);
 	valid_handle = ion_handle_validate(client, handle);
 	if (!valid_handle) {
 		WARN(1, "%s: invalid handle passed to share.\n", __func__);
-		mutex_unlock(&client->lock);
+		if (lock_client)
+			mutex_unlock(&client->lock);
 		return ERR_PTR(-EINVAL);
 	}
 	buffer = handle->buffer;
 	ion_buffer_get(buffer);
-	mutex_unlock(&client->lock);
+	if (lock_client)
+		mutex_unlock(&client->lock);
 
 	exp_info.ops = &dma_buf_ops;
 	exp_info.size = buffer->size;
@@ -1159,14 +1162,21 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
 
 	return dmabuf;
 }
+
+struct dma_buf *ion_share_dma_buf(struct ion_client *client,
+				  struct ion_handle *handle)
+{
+	return __ion_share_dma_buf(client, handle, true);
+}
 EXPORT_SYMBOL(ion_share_dma_buf);
 
-int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
+static int __ion_share_dma_buf_fd(struct ion_client *client,
+				  struct ion_handle *handle, bool lock_client)
 {
 	struct dma_buf *dmabuf;
 	int fd;
 
-	dmabuf = ion_share_dma_buf(client, handle);
+	dmabuf = __ion_share_dma_buf(client, handle, lock_client);
 	if (IS_ERR(dmabuf))
 		return PTR_ERR(dmabuf);
 
@@ -1176,8 +1186,19 @@ int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
 
 	return fd;
 }
+
+int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
+{
+	return __ion_share_dma_buf_fd(client, handle, true);
+}
 EXPORT_SYMBOL(ion_share_dma_buf_fd);
 
+static int ion_share_dma_buf_fd_nolock(struct ion_client *client,
+				       struct ion_handle *handle)
+{
+	return __ion_share_dma_buf_fd(client, handle, false);
+}
+
 struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
 {
 	struct dma_buf *dmabuf;
@@ -1202,7 +1223,7 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
 	/* if a handle exists for this buffer just take a reference to it */
 	handle = ion_handle_lookup(client, buffer);
 	if (!IS_ERR(handle)) {
-		ion_handle_get(handle);
+		handle = ion_handle_get_check_overflow(handle);
 		mutex_unlock(&client->lock);
 		goto end;
 	}
@@ -1324,11 +1345,15 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	{
 		struct ion_handle *handle;
 
-		handle = ion_handle_get_by_id(client, data.handle.handle);
-		if (IS_ERR(handle))
+		mutex_lock(&client->lock);
+		handle = ion_handle_get_by_id_nolock(client, data.handle.handle);
+		if (IS_ERR(handle)) {
+			mutex_unlock(&client->lock);
 			return PTR_ERR(handle);
-		data.fd.fd = ion_share_dma_buf_fd(client, handle);
-		ion_handle_put(handle);
+		}
+		data.fd.fd = ion_share_dma_buf_fd_nolock(client, handle);
+		ion_handle_put_nolock(handle);
+		mutex_unlock(&client->lock);
 		if (data.fd.fd < 0)
 			ret = data.fd.fd;
 		break;