1 /* 2 * Copyright (C) 2010 Dan Carpenter. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 2 7 * of the License, or (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt 16 */ 17 18 #include "smatch.h" 19 20 static void match_snprintf(const char *fn, struct expression *expr, void *unused) 21 { 22 struct expression *dest; 23 struct expression *dest_size_expr; 24 struct expression *format_string; 25 struct expression *data; 26 char *data_name = NULL; 27 int dest_size; 28 sval_t limit_size; 29 char *format; 30 int data_size; 31 32 dest = get_argument_from_call_expr(expr->args, 0); 33 dest_size_expr = get_argument_from_call_expr(expr->args, 1); 34 format_string = get_argument_from_call_expr(expr->args, 2); 35 data = get_argument_from_call_expr(expr->args, 3); 36 37 dest_size = get_array_size_bytes(dest); 38 if (!get_implied_value(dest_size_expr, &limit_size)) 39 return; 40 if (dest_size > 1 && dest_size < limit_size.value) 41 sm_error("snprintf() is printing too much %s vs %d", 42 sval_to_str(limit_size), dest_size); 43 format = expr_to_var(format_string); 44 if (!format) 45 return; 46 if (strcmp(format, "\"%s\"")) 47 goto free; 48 data_name = expr_to_str(data); 49 data_size = get_size_from_strlen(data); 50 if (!data_size) 51 data_size = get_array_size_bytes(data); 52 if (limit_size.value < data_size) 53 sm_error("snprintf() chops off the last chars of '%s': %d vs %s", 54 data_name, data_size, sval_to_str(limit_size)); 55 free: 56 free_string(data_name); 57 free_string(format); 58 } 59 60 void check_snprintf_overflow(int id) 61 { 62 add_function_hook("snprintf", &match_snprintf, NULL); 63 } 64