tools/detect_bad_alloc_patterns.py

   1 """
   2 Detect and replace instances of g_malloc() and wmem_alloc() with
   3 g_new() wmem_new(), to improve the readability of Wireshark's code.
   4
   5 Also detect and replace instances of
   6 g_malloc(sizeof(struct myobj) * foo)
   7 with:
   8 g_new(struct myobj, foo)
   9 to better prevent integer overflows
  10
  11 SPDX-License-Identifier: MIT
  12 """
  13
  14 import os
  15 import re
  16 import sys
  17
  18 print_replacement_info = True
  19
  20 patterns = [
  21 # Replace (myobj *)g_malloc(sizeof(myobj)) with g_new(myobj, 1)
  22 # Replace (struct myobj *)g_malloc(sizeof(struct myobj)) with g_new(struct myobj, 1)
  23 (re.compile(r'\(\s*([struct]{0,6}\s*[^\s\*]+)\s*\*\s*\)\s*g_malloc(0?)\s*\(\s*sizeof\s*\(\s*\1\s*\)\s*\)'), r'g_new\2(\1, 1)'),
  24
  25 # Replace (myobj *)g_malloc(sizeof(myobj) * foo) with g_new(myobj, foo)
  26 # Replace (struct myobj *)g_malloc(sizeof(struct myobj) * foo) with g_new(struct myobj, foo)
  27 (re.compile(r'\(\s*([struct]{0,6}\s*[^\s\*]+)\s*\*\s*\)\s*g_malloc(0?)\s*\(\s*sizeof\s*\(\s*\1\s*\)\s*\*\s*([^\s]+)\s*\)'), r'g_new\2(\1, \3)'),
  28
  29 # Replace (myobj *)g_malloc(foo * sizeof(myobj)) with g_new(myobj, foo)
  30 # Replace (struct myobj *)g_malloc(foo * sizeof(struct myobj)) with g_new(struct myobj, foo)
  31 (re.compile(r'\(\s*([struct]{0,6}\s*[^\s\*]+)\s*\*\s*\)\s*g_malloc(0?)\s*\(\s*([^\s]+)\s*\*\s*sizeof\s*\(\s*\1\s*\)\s*\)'), r'g_new\2(\1, \3)'),
  32
  33 # Replace (myobj *)wmem_alloc(wmem_file_scope(), sizeof(myobj)) with wmem_new(wmem_file_scope(), myobj)
  34 # Replace (struct myobj *)wmem_alloc(wmem_file_scope(), sizeof(struct myobj)) with wmem_new(wmem_file_scope(), struct myobj)
  35 (re.compile(r'\(\s*([struct]{0,6}\s*[^\s\*]+)\s*\*\s*\)\s*wmem_alloc(0?)\s*\(\s*([_a-z\(\)->]+),\s*sizeof\s*\(\s*\1\s*\)\s*\)'), r'wmem_new\2(\3, \1)'),
  36 ]
  37
  38 def replace_file(fpath):
  39     with open(fpath, 'r') as fh:
  40         fdata_orig = fh.read()
  41     fdata = fdata_orig
  42     for pattern, replacewith in patterns:
  43         fdata_out = pattern.sub(replacewith, fdata)
  44         if print_replacement_info and fdata != fdata_out:
  45             for match in re.finditer(pattern, fdata):
  46                 replacement = re.sub(pattern, replacewith, match.group(0))
  47                 print("Bad malloc pattern in %s: Replace '%s' with '%s'" % (fpath, match.group(0), replacement))
  48         fdata = fdata_out
  49     if fdata_out != fdata_orig:
  50         with open(fpath, 'w') as fh:
  51             fh.write(fdata_out)
  52     return fdata_out
  53
  54 def run_specific_files(fpaths):
  55     for fpath in fpaths:
  56         if not (fpath.endswith('.c') or fpath.endswith('.cpp')):
  57             continue
  58         replace_file(fpath)
  59
  60 def run_recursive(root_dir):
  61     for root, dirs, files in os.walk(root_dir):
  62         fpaths = []
  63         for fname in files:
  64             fpath = os.path.join(root, fname)
  65             fpaths.append(fpath)
  66         run_specific_files(fpaths)
  67
  68 def test_replacements():
  69     test_string = """\
  70 (if_info_t*) g_malloc0(sizeof(if_info_t))
  71 (oui_info_t *)g_malloc(sizeof (oui_info_t))
  72 (uint8_t *)g_malloc(16 * sizeof(uint8_t))
  73 (uint32_t *)g_malloc(sizeof(uint32_t)*2)
  74 (struct imf_field *)g_malloc (sizeof (struct imf_field))
  75 (rtspstat_t *)g_malloc( sizeof(rtspstat_t) )
  76 (proto_data_t *)wmem_alloc(scope, sizeof(proto_data_t))
  77 (giop_sub_handle_t *)wmem_alloc(wmem_epan_scope(), sizeof (giop_sub_handle_t))
  78 (mtp3_addr_pc_t *)wmem_alloc0(pinfo->pool, sizeof(mtp3_addr_pc_t))
  79 (dcerpc_bind_value *)wmem_alloc(wmem_file_scope(), sizeof (dcerpc_bind_value))
  80 (dcerpc_matched_key *)wmem_alloc(wmem_file_scope(), sizeof (dcerpc_matched_key));
  81 (struct smtp_session_state *)wmem_alloc0(wmem_file_scope(), sizeof(struct smtp_session_state))
  82 (struct batman_packet_v5 *)wmem_alloc(pinfo->pool, sizeof(struct batman_packet_v5))
  83 (struct knx_keyring_mca_keys*) wmem_alloc( wmem_epan_scope(), sizeof( struct knx_keyring_mca_keys ) )
  84 """
  85     expected_output = """\
  86 g_new0(if_info_t, 1)
  87 g_new(oui_info_t, 1)
  88 g_new(uint8_t, 16)
  89 g_new(uint32_t, 2)
  90 g_new(struct imf_field, 1)
  91 g_new(rtspstat_t, 1)
  92 wmem_new(scope, proto_data_t)
  93 wmem_new(wmem_epan_scope(), giop_sub_handle_t)
  94 wmem_new0(pinfo->pool, mtp3_addr_pc_t)
  95 wmem_new(wmem_file_scope(), dcerpc_bind_value)
  96 wmem_new(wmem_file_scope(), dcerpc_matched_key);
  97 wmem_new0(wmem_file_scope(), struct smtp_session_state)
  98 wmem_new(pinfo->pool, struct batman_packet_v5)
  99 wmem_new(wmem_epan_scope(), struct knx_keyring_mca_keys)
 100 """
 101     output = test_string
 102     for pattern, replacewith in patterns:
 103         output = pattern.sub(replacewith, output)
 104     assert(output == expected_output)
 105
 106 def main():
 107     test_replacements()
 108     if len(sys.argv) == 2:
 109         root_dir = sys.argv[1]
 110         run_recursive(root_dir)
 111     else:
 112         fpaths = []
 113         for line in sys.stdin:
 114             line = line.strip()
 115             if line:
 116                 fpaths.append(line)
 117         run_specific_files(fpaths)
 118
 119 if __name__ == "__main__":
 120     main()