malloc_search.py

#!/usr/bin/python

# License: MIT
# Author: Michael Scovetta <[email protected]>

import re
import sys

"""
Usage:

Do an initial grep through the source tree and xargs the results over to this script, e.g.:

grep -FlRi 'alloc' freebsd_src | xargs -n1 -P6 python malloc.py

"""


"""
The MALLOCs here are malloc-like functions. You can find some of them with this:
egrep -hoRi "[a-z_]*alloc\s*\(" freebsd_src | sort | uniq -c | sort -n
"""
MALLOCS = ['malloc', 'realloc', 'alloc', 'xmalloc', 'os_malloc', 'os_zalloc', '_malloc', 'g_malloc']

if len(sys.argv) != 2:
	print('Usage: python malloc_search.py filename')
	sys.exit(1)

filename = sys.argv[1]

with open(filename) as f:
	lines = map(str.strip, f)
	for line_number, line in enumerate(lines):
		for malloc in MALLOCS:
			# First, we check to see if we match the general malloc pattern, with optional cast.
			matches = re.match(r'.*(?:\((.+\s*\*)\)\s*)?' + malloc + r'\s*\((.+)\)\s*;$', line, re.IGNORECASE)
			if not matches:
				continue	# Missing the initial malloc pattern

			cast_param = matches.group(1)
			if cast_param:
				cast_param = cast_param.replace('*', '').strip()
			malloc_params = matches.group(2)

			sizeof_matches = re.search(r'sizeof\s*\(([^\)]+)\)', malloc_params)
			if sizeof_matches:
				sizeof_param = sizeof_matches.group(1)
			else:
				continue   # Must have a sizeof operator
			
			var_matches = re.search(r'([a-z][a-z0-9_]*)\s*\*\s*sizeof', malloc_params)
			if not var_matches:
				var_matches = re.search(r'sizeof\s*\([^\)]+\)\s*\*\s*([a-z][a-z0-9_]*)', malloc_params, re.IGNORECASE)
			if not var_matches:
				continue	# We need a multiplicative offset
			var_param = var_matches.group(1)

			const_matches = re.match(r'.*(\+\s*\d+)\s*$', malloc_params)
			if not const_matches:
				const_matches = re.match(r'^\s*(\d+\s*\+).*', malloc_params)
			if not const_matches:
				continue	# Must have a constant offset
			const_param = const_matches.group(1)

			print("************************")
			print("Found a potential match:")
			print(" Filename: {0}:{1}".format(filename, line_number))
			print(" Offending Line: {0}".format(line))

			print(" Variable assignments found at:")
			for var_line_number, var_line in enumerate(lines):
				if var_line_number >= line_number:
					break	# Only looking upward
				if re.search(r'(^|\b)' + re.escape(var_param) + r'\s*=[^=]', var_line, re.IGNORECASE):
					print("\t{0} {1}".format(var_line_number, var_line))

			print(" Variable usage found at:")
			for var_line_number, var_line in enumerate(lines):
				if var_line_number >= line_number:
					break	# Only looking upward
				if var_param in var_line:
					print("\t{0} {1}".format(var_line_number + 1, var_line))				

			print("")
			break

Results from running against github.com/freebsd/freebsd/tree/master

************************
Found a potential match:
 Filename: freebsd/contrib/binutils/libiberty/argv.c:412
 Offending Line: buffer = (char *) xmalloc (pos * sizeof (char) + 1);
 Variable assignments found at:
        407 pos = ftell (f);
 Variable usage found at:
        142 If the input is a null string (as opposed to a @code{NULL} pointer),
        386 long pos;
        408 pos = ftell (f);
        409 if (pos == -1)

************************
Found a potential match:
 Filename: freebsd/contrib/gcclibs/libiberty/argv.c:359
 Offending Line: buffer = (char *) xmalloc (pos * sizeof (char) + 1);
 Variable assignments found at:
        354 pos = ftell (f);
 Variable usage found at:
        142 If the input is a null string (as opposed to a @code{NULL} pointer),
        333 long pos;
        355 pos = ftell (f);
        356 if (pos == -1)

************************
Found a potential match:
 Filename: freebsd/contrib/sqlite3/shell.c:6970
 Offending Line: pNew = (IdxConstraint*)idxMalloc(pRc, sizeof(IdxConstraint) * nColl + 1);
 Variable assignments found at:
        6967 int nColl = STRLEN(zColl);
 Variable usage found at:
        6968 int nColl = STRLEN(zColl);

************************
Found a potential match:
 Filename: freebsd/contrib/subversion/subversion/libsvn_subr/utf8proc/utf8proc.c:708
 Offending Line: buffer = (utf8proc_int32_t *) malloc(result * sizeof(utf8proc_int32_t) + 1);
 Variable assignments found at:
        706 result = utf8proc_decompose_custom(str, strlen, NULL, 0, options, custom_func, custom_data);
 Variable usage found at:
        245 and are thus not handled by this function. This may result in an incorrect break before
        506 utf8proc_ssize_t decomp_result;
        524 decomp_result = utf8proc_decompose_char(
        528 if (decomp_result < 0) return decomp_result;
        529 wpos += decomp_result;
        705 utf8proc_ssize_t result;
        707 result = utf8proc_decompose_custom(str, strlen, NULL, 0, options, custom_func, custom_data);
        708 if (result < 0) return result;

************************
Found a potential match:
 Filename: freebsd/contrib/subversion/subversion/libsvn_subr/win32_crashrpt.c:71
 Offending Line: char *utf8_str = malloc(sizeof(wchar_t) * len + 1);
 Variable assignments found at:
        70 size_t len = wcslen(str);
 Variable usage found at:
        71 size_t len = wcslen(str);

************************
Found a potential match:
 Filename: freebsd/contrib/unbound/validator/autotrust.c:169
 Offending Line: char* comment = (char*) malloc(sizeof(char)*len+1);
 Variable assignments found at:
        168 int len = (int)strlen(str), pos = 0, timestamp = 0;
 Variable usage found at:
        125 return (int)(pos-str)+(int)strlen(sub);
        147 char* str = sldns_wire2str_dname(ta->rr, ta->dname_len);
        149 ta->rr, ta->rr_len, ta->dname_len),
        150 sldns_wirerr_get_rdatalen(ta->rr, ta->rr_len,
        151 ta->dname_len));
        169 int len = (int)strlen(str), pos = 0, timestamp = 0;

************************
Found a potential match:
 Filename: freebsd/usr.bin/sdiff/sdiff.c:263
 Offending Line: diffargv[1]  = realloc(diffargv[1], sizeof(char) * strlen(diffargv[1]) + 2);
 Variable assignments found at:
 Variable usage found at: