1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * This is for all the tests relating directly to Control Flow Integrity. 4 */ 5 #include "lkdtm.h" 6 7 static int called_count; 8 9 /* Function taking one argument, without a return value. */ 10 static noinline void lkdtm_increment_void(int *counter) 11 { 12 (*counter)++; 13 } 14 15 /* Function taking one argument, returning int. */ 16 static noinline int lkdtm_increment_int(int *counter) 17 { 18 (*counter)++; 19 20 return *counter; 21 } 22 /* 23 * This tries to call an indirect function with a mismatched prototype. 24 */ 25 void lkdtm_CFI_FORWARD_PROTO(void) 26 { 27 /* 28 * Matches lkdtm_increment_void()'s prototype, but not 29 * lkdtm_increment_int()'s prototype. 30 */ 31 void (*func)(int *); 32 33 pr_info("Calling matched prototype ...\n"); 34 func = lkdtm_increment_void; 35 func(&called_count); 36 37 pr_info("Calling mismatched prototype ...\n"); 38 func = (void *)lkdtm_increment_int; 39 func(&called_count); 40 41 pr_err("FAIL: survived mismatched prototype function call!\n"); 42 pr_expected_config(CONFIG_CFI_CLANG); 43 } 44