ACPICA: Add safe versions of common string functions.

This change adds and deploys "safe" versions of strcpy and strcat that
ensure that the target buffer does not overflow. These safe functions
are only helpful for processing user input and command lines. For most
ACPICA code however, the required buffer length is precisely calculated
before buffer allocation, so the use of these functions is unnecessary.
ACPICA BZ 1043.

This change only applies to the ACPICA utilities and the debugger, none
of which are not shipped with the kernel yet, so the kernel's behavior
remains unchanged after it.

References: https://bugs.acpica.org/show_bug.cgi?id=1043
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/utstring.c b/drivers/acpi/acpica/utstring.c
index cb1e9cc32d5f..5ef41ffcf575 100644
--- a/drivers/acpi/acpica/utstring.c
+++ b/drivers/acpi/acpica/utstring.c
@@ -584,3 +584,65 @@ void ut_convert_backslashes(char *pathname)
 	}
 }
 #endif
+
+#if defined (ACPI_DEBUGGER) || defined (ACPI_APPLICATION)
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ut_safe_strcpy, acpi_ut_safe_strcat, acpi_ut_safe_strncat
+ *
+ * PARAMETERS:  Adds a "DestSize" parameter to each of the standard string
+ *              functions. This is the size of the Destination buffer.
+ *
+ * RETURN:      TRUE if the operation would overflow the destination buffer.
+ *
+ * DESCRIPTION: Safe versions of standard Clib string functions. Ensure that
+ *              the result of the operation will not overflow the output string
+ *              buffer.
+ *
+ * NOTE:        These functions are typically only helpful for processing
+ *              user input and command lines. For most ACPICA code, the
+ *              required buffer length is precisely calculated before buffer
+ *              allocation, so the use of these functions is unnecessary.
+ *
+ ******************************************************************************/
+
+u8 acpi_ut_safe_strcpy(char *dest, acpi_size dest_size, char *source)
+{
+
+	if (ACPI_STRLEN(source) >= dest_size) {
+		return (TRUE);
+	}
+
+	ACPI_STRCPY(dest, source);
+	return (FALSE);
+}
+
+u8 acpi_ut_safe_strcat(char *dest, acpi_size dest_size, char *source)
+{
+
+	if ((ACPI_STRLEN(dest) + ACPI_STRLEN(source)) >= dest_size) {
+		return (TRUE);
+	}
+
+	ACPI_STRCAT(dest, source);
+	return (FALSE);
+}
+
+u8
+acpi_ut_safe_strncat(char *dest,
+		     acpi_size dest_size,
+		     char *source, acpi_size max_transfer_length)
+{
+	acpi_size actual_transfer_length;
+
+	actual_transfer_length =
+	    ACPI_MIN(max_transfer_length, ACPI_STRLEN(source));
+
+	if ((ACPI_STRLEN(dest) + actual_transfer_length) >= dest_size) {
+		return (TRUE);
+	}
+
+	ACPI_STRNCAT(dest, source, max_transfer_length);
+	return (FALSE);
+}
+#endif