可变参数中size_t遇见的问题
Posted taek
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在修改php扩展Trie时,出现了一个小bug
PHP_FUNCTION(trie_filter_load) { Trie *trie; char *path; int path_len; if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &path, &path_len) == FAILURE) { RETURN_NULL(); } if(path !=NULL){ php_printf("path is not null\\n"); php_printf("path address is %x\\n", path); } trie = trie_new_from_file(path); if (!trie) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Unable to load %s", path); RETURN_NULL(); } RETURN_RES(zend_register_resource(trie, le_trie_filter)); }
注意这个 path_len的类型为int
运行结果为
start print the path
print the path
the path is not null
the path address is 0x7fdd00000000
Segmentation fault
#设置core大小为无限,从而产生core文件
ulimit -c unlimited
gdb /usr/local/php-7.1.6/bin/php core.22772
core was generated by `/usr/local/php-7.1.6/bin/php test.php\'. Program terminated with signal 11, Segmentation fault. #0 0x00007fb3433bb301 in __strlen_sse2 () from /lib64/libc.so.6 Missing separate debuginfos, use: debuginfo-install cyrus-sasl-lib-2.1.23-15.el6_6.2.x86_64 glibc-2.12-1.192.el6.x86_64 keyutils-libs-1.4-5.el6.x86_64 krb5-libs-1.10.3-57.el6.x86_64 libcom_err-1.41.12-22.el6.x86_64 libcurl-7.19.7-53.el6_9.x86_64 libidn-1.18-2.el6.x86_64 libselinux-2.0.94-7.el6.x86_64 libssh2-1.4.2-2.el6_7.1.x86_64 libxml2-2.7.6-21.el6_8.1.x86_64 nspr-4.13.1-1.el6.x86_64 nss-3.28.4-3.el6_9.x86_64 nss-softokn-freebl-3.14.3-23.el6_7.x86_64 nss-util-3.28.4-1.el6_9.x86_64 openldap-2.4.40-12.el6.x86_64 openssl-1.0.1e-57.el6.x86_64 (gdb) where #0 0x00007fb3433bb301 in __strlen_sse2 () from /lib64/libc.so.6 #1 0x000000000093d5c5 in xbuf_format_converter (xbuf=0x7ffc60473cf0, is_char=1 \'\\001\', fmt=0x7fb33a76c0c8 "trie_filter_search_all", ap=0x7ffc60473e60) at /home/source/php-7.1.6/main/spprintf.c:605 #2 0x000000000093e762 in vspprintf (pbuf=0x7ffc60473da8, max_len=0, format=0x7fb33a76c0b8 "e_filter_search", ap=0x7ffc60473e60) at /home/source/php-7.1.6/main/spprintf.c:843 #3 0x00000000009345e1 in php_verror (docref=0x0, params=0x1031a72 "", type=2, format=0x7fb33a76c0b8 "e_filter_search", args=0x7ffc60473e60) at /home/source/php-7.1.6/main/main.c:762 #4 0x0000000000935075 in php_error_docref0 (docref=0x0, type=2, format=0x7fb33a76c0b8 "e_filter_search") at /home/source/php-7.1.6/main/main.c:949 #5 0x00007fb33a76b4ea in zif_trie_filter_load (execute_data=0x7fb340814260, return_value=0x7fb340814200) at /home/source/php-7.1.8/ext/php-ext-trie-filter/trie_filter.c:124 #6 0x0000000000a317f9 in ZEND_DO_ICALL_SPEC_RETVAL_USED_HANDLER (execute_data=0x7fb3408140d0) at /home/source/php-7.1.6/Zend/zend_vm_execute.h:675 #7 0x0000000000a30e53 in execute_ex (ex=0x7fb340814030) at /home/source/php-7.1.6/Zend/zend_vm_execute.h:432 #8 0x0000000000a30fa4 in zend_execute (op_array=0x7fb34086d100, return_value=0x0) at /home/source/php-7.1.6/Zend/zend_vm_execute.h:474 #9 0x00000000009d0543 in zend_execute_scripts (type=8, retval=0x0, file_count=3) at /home/source/php-7.1.6/Zend/zend.c:1476 #10 0x00000000009386de in php_execute_script (primary_file=0x7ffc60477580) at /home/source/php-7.1.6/main/main.c:2537 #11 0x0000000000ac4ab6 in do_cli (argc=2, argv=0x2b1cb70) at /home/source/php-7.1.6/sapi/cli/php_cli.c:993 #12 0x0000000000ac59f5 in main (argc=2, argv=0x2b1cb70) at /home/source/php-7.1.6/sapi/cli/php_cli.c:1381 (gdb)
发现是 调用 __strlen_sse2 时出现问题，利用where 找到调用 的 __strlen_sse2的栈帧, 估计bt也可以吧
就是说path指针 指向了 地址为0x7fdd00000000的内存,但在执行__strlen_sse2的时候 出问题了，说明这个内存地址 有问题
而 /home/source/php-7.1.6/main/spprintf.c:605 的代码是
case \'s\': case \'v\': s = va_arg(ap, char *); if (s != NULL) { if (!adjust_precision) { s_len = strlen(s); //506行 } else { s_len = strnlen(s, precision); } } else { s = S_NULL; s_len = S_NULL_LEN; } pad_char = \' \'; break;
解决方法
1）目前调用的函数是trie_filter_load, 但在扩展中是zif_trie_filter_load
利用nm找到在扩展中找到
[root@www ~]# nm /usr/local/php-7.1.6/lib/php/extensions/debug-non-zts-20160303/trie_filter.so|grep trie_filter_load 00000000000014bd T zif_trie_filter_load
2）利用gdb调试
gdb /usr/local/php-7.1.6/bin/php
(gdb) br zif_trie_filter_load
(gdb) r ./test.php
Breakpoint 1, zif_trie_filter_load (execute_data=0x7ffff2e14260, return_value=0x7ffff2e14200)
at /home/source/php-7.1.8/ext/php-ext-trie-filter/trie_filter.c:125
warning: Source file is more recent than executable.
125 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s",
(gdb) n
(gdb) p path
$1 = 0x7fff00000000 <Address 0x7fff00000000 out of bounds>
地址居然越界了
可以肯定的是在执行 php_error_docref时报错了
稍带看下zend_parse_parameter的原理，其参数 是 可变参数
ZEND_API int zend_parse_parameters(int num_args, const char *type_spec, ...) /* {{{ */ { va_list va; int retval; int flags = 0; va_start(va, type_spec); retval = zend_parse_va_args(num_args, type_spec, &va, flags); va_end(va); return retval; }
static int zend_parse_va_args(int num_args, const char *type_spec, va_list *va, int flags) /* {{{ */ { const char *spec_walk; int c, i; int min_num_args = -1; int max_num_args = 0; int post_varargs = 0; zval *arg; int arg_count; zend_bool have_varargs = 0; zval **varargs = NULL; int *n_varargs = NULL; for (spec_walk = type_spec; *spec_walk; spec_walk++) { c = *spec_walk; switch (c) { case \'l\': case \'d\': case \'s\': case \'b\': case \'r\': case \'a\': case \'o\': case \'O\': case \'z\': case \'Z\': case \'C\': case \'h\': case \'f\': case \'A\': case \'H\': case \'p\': case \'S\': case \'P\': case \'L\': max_num_args++; break; case \'|\': min_num_args = max_num_args; break; case \'/\': case \'!\': /* Pass */ break; case \'*\': case \'+\': if (have_varargs) { zend_parse_parameters_debug_error( "only one varargs specifier (* or +) is permitted"); return FAILURE; } have_varargs = 1; /* we expect at least one parameter in varargs */ if (c == \'+\') { max_num_args++; } /* mark the beginning of varargs */ post_varargs = max_num_args; break; default: zend_parse_parameters_debug_error("bad type specifier while parsing parameters"); return FAILURE; } } if (min_num_args < 0) { min_num_args = max_num_args; } if (have_varargs) { /* calculate how many required args are at the end of the specifier list */ post_varargs = max_num_args - post_varargs; max_num_args = -1; } if (num_args < min_num_args || (num_args > max_num_args && max_num_args >= 0)) { if (!(flags & ZEND_PARSE_PARAMS_QUIET)) { zend_function *active_function = EG(current_execute_data)->func; const char *class_name = active_function->common.scope ? ZSTR_VAL(active_function->common.scope->name) : ""; zend_bool throw_exception = ZEND_ARG_USES_STRICT_TYPES() || (flags & ZEND_PARSE_PARAMS_THROW); zend_internal_argument_count_error(throw_exception, "%s%s%s() expects %s %d parameter%s, %d given", class_name, class_name[0] ? "::" : "", ZSTR_VAL(active_function->common.function_name), min_num_args == max_num_args ? "exactly" : num_args < min_num_args ? "at least" : "at most", num_args < min_num_args ? min_num_args : max_num_args, (num_args < min_num_args ? min_num_args : max_num_args) == 1 ? "" : "s", num_args); } return FAILURE; } arg_count = ZEND_CALL_NUM_ARGS(EG(current_execute_data)); if (num_args > arg_count) { zend_parse_parameters_debug_error("could not obtain parameters for parsing"); return FAILURE; } i = 0; while (num_args-- > 0) { if (*type_spec == \'|\') { type_spec++; } if (*type_spec == \'*\' || *type_spec == \'+\') { int num_varargs = num_args + 1 - post_varargs; /* eat up the passed in storage even if it won\'t be filled in with varargs */ varargs = va_arg(*va, zval **); n_varargs = va_arg(*va, int *); type_spec++; if (num_varargs > 0) { *n_varargs = num_varargs; *varargs = ZEND_CALL_ARG(EG(current_execute_data), i + 1); /* adjust how many args we have left and restart loop */ num_args += 1 - num_varargs; i += num_varargs; continue; } else { *varargs = NULL; *n_varargs = 0; } } arg = ZEND_CALL_ARG(EG(current_execute_data), i + 1); if (zend_parse_arg(i+1, arg, va, &type_spec, flags) == FAILURE) { /* clean up varargs array if it was used */ if (varargs && *varargs) { *varargs = NULL; } return FAILURE; } i++; } return SUCCESS; } /* }}} */
static int zend_parse_arg(int arg_num, zval *arg, va_list *va, const char **spec, int flags) /* {{{ */ { const char *expected_type = NULL; char *error = NULL; int severity = 0; expected_type = zend_parse_arg_impl(arg_num, arg, va, spec, &error, &severity); if (expected_type) { if (!(flags & ZEND_PARSE_PARAMS_QUIET) && (*expected_type || error)) { const char *space; const char *class_name = get_active_class_name(&space); zend_bool throw_exception = ZEND_ARG_USES_STRICT_TYPES() || (flags & ZEND_PARSE_PARAMS_THROW); if (error) { zend_internal_type_error(throw_exception, "%s%s%s() expects parameter %d %s", class_name, space, get_active_function_name(), arg_num, error); efree(error); } else { zend_internal_type_error(throw_exception, "%s%s%s() expects parameter %d to be %s, %s given", class_name, space, get_active_function_name(), arg_num, expected_type, zend_zval_type_name(arg)); } } if (severity != E_DEPRECATED) { return FAILURE; } } return SUCCESS; } /* }}} */
因为传入的是string,所以进入case \'s\',其接收的类型为size_t,即
因为执行该程序所在的机器是x86 64位，size_t的宏定义为 typedef unsigned long size_t;
如果机器是x86 32位，size_t宏的定义为 typedef unsigned int size_t;
定义是int类型，接收为unsigned long 肯定不行啊
关于可变参数的原理，详见这里
static const char *zend_parse_arg_impl(int arg_num, zval *arg, va_list *va, const char **spec, char **error, int *severity) /* {{{ */ { const char *spec_walk = *spec; char c = *spec_walk++; int check_null = 0; int separate = 0; zval *real_arg = arg; /* scan through modifiers */ ZVAL_DEREF(arg); while (1) { if (*spec_walk == \'/\') { SEPARATE_ZVAL_NOREF(arg); real_arg = arg; separate = 1; } else if (*spec_walk == \'!\') { check_null = 1; } else { break; } spec_walk++; } switch (c) { case \'l\': case \'L\': { zend_long *p = va_arg(*va, zend_long *); zend_bool *is_null = NULL; if (check_null) { is_null = va_arg(*va, zend_bool *); } if (!zend_parse_arg_long(arg, p, is_null, check_null, c == \'L\')) { return "integer"; } } break; case \'d\': { double *p = va_arg(*va, double *); zend_bool *is_null = NULL; if (check_null) { is_null = va_arg(*va, zend_bool *); } if (!zend_parse_arg_double(arg, p, is_null, check_null)) { return "float"; } } break; case \'s\': { char **p = va_arg(*va, char **); size_t *pl = va_arg(*va, size_t *); if (!zend_parse_arg_string(arg, p, pl, check_null)) { return "string"; } } break; case \'p\': { char **p = va_arg(*va, char **); size_t *pl = va_arg(*va, size_t *); if (!zend_parse_arg_path(arg, p, pl, check_null)) { return "a valid path"; } } break; case \'P\': { zend_string **str = va_arg(*va, zend_string **); if (!zend_parse_arg_path_str(arg, str, check_null)) { return "a valid path"; } } break; case \'S\': { zend_string **str = va_arg(*va, zend_string **); if (!zend_parse_arg_str(arg, str, check_null)) { return "string"; } } break; case \'b\': { zend_bool *p = va_arg(*va, zend_bool *); zend_bool *is_null = NULL; if (check_null) { is_null = va_arg(*va, zend_bool *); } if (!zend_parse_arg_bool(arg, p, is_null, check_null)) { return "boolean"; } } break; case \'r\': { zval **p = va_arg(*va, zval **); if (!zend_parse_arg_resource(arg, p, check_null)) { return "resource"; } } break; case \'A\': case \'a\': { zval **p = va_arg(*va, zval **); if (!zend_parse_arg_array(arg, p, check_null, c == \'A\')) { return "array"; } } break; case \'H\': case \'h\': { HashTable **p = va_arg(*va, HashTable **); if (!zend_parse_arg_array_ht(arg, p, check_null, c == \'H\', separate)) { return "array"; } } break; case \'o\': { zval **p = va_arg(*va, zval **); if (!zend_parse_arg_object(arg, p, NULL, check_null)) { return "object"; } } break; case \'O\': { zval **p = va_arg(*va, zval **); zend_class_entry *ce = va_arg(*va, zend_class_entry *); if (!zend_parse_arg_object(arg, p, ce, check_null)) { if (ce) { return ZSTR_VAL(ce->name); } else { return "object"; } } } break; case \'C\': { zend_class_entry *lookup, **pce = va_arg(*va, zend_class_entry **); zend_class_entry *ce_base = *pce; if (check_null && Z_TYPE_P(arg) == IS_NULL) { *pce = NULL; break; } convert_to_string_ex(arg); if ((lookup = zend_lookup_class(Z_STR_P(arg))) == NULL) { *pce = NULL; } else { *pce = lookup; } if (ce_base) { if ((!*pce || !instanceof_function(*pce, ce_base))) { zend_spprintf(error, 0, "to be a class name derived from %s, \'%s\' given", ZSTR_VAL(ce_base->name), Z_STRVAL_P(arg)); *pce = NULL; return ""; } } if (!*pce) { zend_spprintf(error, 0, "to be a valid class name, \'%s\' given", Z_STRVAL_P(arg)); return ""; } break; } break; case \'f\': { zend_fcall_info *fci = va_arg(*va, zend_fcall_info *); zend_fcall_info_cache *fcc = va_arg(*va, zend_fcall_info_cache *); char *is_callable_error = NULL; if (check_null && Z_TYPE_P(arg) == IS_NULL) { fci->size = 0以上是关于可变参数中size_t遇见的问题的主要内容，如果未能解决你的问题，请参考以下文章