VMCI: Fix integer overflow in VMCI handle arrays

The VMCI handle array has an integer overflow in
vmci_handle_arr_append_entry when it tries to expand the array. This can be
triggered from a guest, since the doorbell link hypercall doesn't impose a
limit on the number of doorbell handles that a VM can create in the
hypervisor, and these handles are stored in a handle array.

In this change, we introduce a mandatory max capacity for handle
arrays/lists to avoid excessive memory usage.

Signed-off-by: Vishnu Dasa <vdasa@vmware.com>
Reviewed-by: Adit Ranadive <aditr@vmware.com>
Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 19 insertions, 10 deletions

diff --git a/drivers/misc/vmw_vmci/vmci_handle_array.h b/drivers/misc/vmw_vmci/vmci_handle_array.h
index bd1559a548e9..96193f85be5b 100644
--- a/drivers/misc/vmw_vmci/vmci_handle_array.h
+++ b/drivers/misc/vmw_vmci/vmci_handle_array.h
@@ -9,32 +9,41 @@
 #define _VMCI_HANDLE_ARRAY_H_
 
 #include <linux/vmw_vmci_defs.h>
+#include <linux/limits.h>
 #include <linux/types.h>
 
-#define VMCI_HANDLE_ARRAY_DEFAULT_SIZE 4
-#define VMCI_ARR_CAP_MULT 2	/* Array capacity multiplier */
-
 struct vmci_handle_arr {
-	size_t capacity;
-	size_t size;
+	u32 capacity;
+	u32 max_capacity;
+	u32 size;
+	u32 pad;
 	struct vmci_handle entries[];
 };
 
-struct vmci_handle_arr *vmci_handle_arr_create(size_t capacity);
+#define VMCI_HANDLE_ARRAY_HEADER_SIZE				\
+	offsetof(struct vmci_handle_arr, entries)
+/* Select a default capacity that results in a 64 byte sized array */
+#define VMCI_HANDLE_ARRAY_DEFAULT_CAPACITY			6
+/* Make sure that the max array size can be expressed by a u32 */
+#define VMCI_HANDLE_ARRAY_MAX_CAPACITY				\
+	((U32_MAX - VMCI_HANDLE_ARRAY_HEADER_SIZE - 1) /	\
+	sizeof(struct vmci_handle))
+
+struct vmci_handle_arr *vmci_handle_arr_create(u32 capacity, u32 max_capacity);
 void vmci_handle_arr_destroy(struct vmci_handle_arr *array);
-void vmci_handle_arr_append_entry(struct vmci_handle_arr **array_ptr,
-				  struct vmci_handle handle);
+int vmci_handle_arr_append_entry(struct vmci_handle_arr **array_ptr,
+				 struct vmci_handle handle);
 struct vmci_handle vmci_handle_arr_remove_entry(struct vmci_handle_arr *array,
 						struct vmci_handle
 						entry_handle);
 struct vmci_handle vmci_handle_arr_remove_tail(struct vmci_handle_arr *array);
 struct vmci_handle
-vmci_handle_arr_get_entry(const struct vmci_handle_arr *array, size_t index);
+vmci_handle_arr_get_entry(const struct vmci_handle_arr *array, u32 index);
 bool vmci_handle_arr_has_entry(const struct vmci_handle_arr *array,
 			       struct vmci_handle entry_handle);
 struct vmci_handle *vmci_handle_arr_get_handles(struct vmci_handle_arr *array);
 
-static inline size_t vmci_handle_arr_get_size(
+static inline u32 vmci_handle_arr_get_size(
 	const struct vmci_handle_arr *array)
 {
 	return array->size;