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Commit b522a6ce authored by Tor Didriksen's avatar Tor Didriksen
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Bug#11761576 54082: HANDLE_SEGFAULT MAKES USE OF UNSAFE FUNCTIONS 

handle_segfault is the signal handler code of mysqld.  however, it makes
calls to potentially unsafe functions localtime_r, fprintf, fflush.



include/my_stacktrace.h:
  Add safe versions of itoa() write() and snprintf().
libmysqld/CMakeLists.txt:
  Move signal handler to separate file.
mysys/stacktrace.c:
  Remove unsafe function calls.
sql/CMakeLists.txt:
  Move signal handler to separate file.
sql/mysqld.cc:
  Move signal handler to separate file.
sql/set_var.h:
  Add missing #include dependency.
sql/sys_vars.cc:
  Cleanup .h and .cc files.
sql/sys_vars.h:
  Cleanup .h and .cc files.
parent 8e6d41e2
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Showing with 435 additions and 304 deletions
include/my_stacktrace.h
View file @ b522a6ce
/* Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
/* Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
......@@ -59,6 +59,69 @@ void my_set_exception_pointers(EXCEPTION_POINTERS *ep);
void my_write_core(int sig);
#endif
/**
Async-signal-safe utility functions used by signal handler routines.
Declared here in order to unit-test them.
These are not general-purpose, but tailored to the signal handling routines.
*/
/**
Converts a longlong value to string.
@param base 10 for decimal, 16 for hex values (0..9a..f)
@param val The value to convert
@param buf Assumed to point to the *end* of the buffer.
@returns Pointer to the first character of the converted string.
Negative values:
for base-10 the return string will be prepended with '-'
for base-16 the return string will contain 16 characters
Implemented with simplicity, and async-signal-safety in mind.
*/
char *my_safe_itoa(int base, longlong val, char *buf);
/**
Converts a ulonglong value to string.
@param base 10 for decimal, 16 for hex values (0..9a..f)
@param val The value to convert
@param buf Assumed to point to the *end* of the buffer.
@returns Pointer to the first character of the converted string.
Implemented with simplicity, and async-signal-safety in mind.
*/
char *my_safe_utoa(int base, ulonglong val, char *buf);
/**
A (very) limited version of snprintf.
@param to Destination buffer.
@param n Size of destination buffer.
@param fmt printf() style format string.
@returns Number of bytes written, including terminating '\0'
Supports 'd' 'i' 'u' 'x' 'p' 's' conversion.
Supports 'l' and 'll' modifiers for integral types.
Does not support any width/precision.
Implemented with simplicity, and async-signal-safety in mind.
*/
size_t my_safe_snprintf(char* to, size_t n, const char* fmt, ...)
ATTRIBUTE_FORMAT(printf, 3, 4);
/**
A (very) limited version of snprintf, which writes the result to STDERR.
@sa my_safe_snprintf
Implemented with simplicity, and async-signal-safety in mind.
@note Has an internal buffer capacity of 512 bytes,
which should suffice for our signal handling routines.
*/
size_t my_safe_printf_stderr(const char* fmt, ...)
ATTRIBUTE_FORMAT(printf, 1, 2);
/**
Writes up to count bytes from buffer to STDERR.
Implemented with simplicity, and async-signal-safety in mind.
@param buf Buffer containing data to be written.
@param count Number of bytes to write.
@returns Number of bytes written.
*/
size_t my_write_stderr(const void *buf, size_t count);
C_MODE_END
#endif /* _my_stacktrace_h_ */
libmysqld/CMakeLists.txt
View file @ b522a6ce
......@@ -45,6 +45,7 @@ SET(SQL_EMBEDDED_SOURCES emb_qcache.cc libmysqld.c lib_sql.cc
../sql/password.c ../sql/discover.cc ../sql/derror.cc
../sql/field.cc ../sql/field_conv.cc
../sql/filesort.cc ../sql/gstream.cc
../sql/signal_handler.cc
../sql/handler.cc ../sql/hash_filo.cc ../sql/hostname.cc
../sql/init.cc ../sql/item_buff.cc ../sql/item_cmpfunc.cc
../sql/item.cc ../sql/item_create.cc ../sql/item_func.cc
......
mysys/stacktrace.c
View file @ b522a6ce
This diff is collapsed.
sql/CMakeLists.txt
View file @ b522a6ce
......@@ -41,6 +41,7 @@ SET (SQL_SOURCE
../sql-common/client.c derror.cc des_key_file.cc
discover.cc ../libmysql/errmsg.c field.cc field_conv.cc
filesort.cc gstream.cc sha2.cc
signal_handler.cc
handler.cc hash_filo.h sql_plugin_services.h
hostname.cc init.cc item.cc item_buff.cc item_cmpfunc.cc
item_create.cc item_func.cc item_geofunc.cc item_row.cc
......
sql/mysqld.cc
View file @ b522a6ce
......@@ -144,9 +144,6 @@ extern "C" { // Because of SCO 3.2V4.2
#ifdef __WIN__
#include <crtdbg.h>
#define SIGNAL_FMT "exception 0x%x"
#else
#define SIGNAL_FMT "signal %d"
#endif
#ifdef HAVE_SOLARIS_LARGE_PAGES
......@@ -256,7 +253,7 @@ inline void setup_fpu()
extern "C" int gethostname(char *name, int namelen);
#endif
extern "C" sig_handler handle_segfault(int sig);
extern "C" sig_handler handle_fatal_signal(int sig);
#if defined(__linux__)
#define ENABLE_TEMP_POOL 1
......@@ -323,6 +320,10 @@ static PSI_rwlock_key key_rwlock_openssl;
#endif
#endif /* HAVE_PSI_INTERFACE */
#ifdef HAVE_NPTL
volatile sig_atomic_t ld_assume_kernel_is_set= 0;
#endif
/* the default log output is log tables */
static bool lower_case_table_names_used= 0;
static bool max_long_data_size_used= false;
......@@ -333,7 +334,7 @@ static my_bool opt_debugging= 0, opt_external_locking= 0, opt_console= 0;
static my_bool opt_short_log_format= 0;
static uint kill_cached_threads, wake_thread;
static ulong killed_threads;
static ulong max_used_connections;
ulong max_used_connections;
static volatile ulong cached_thread_count= 0;
static char *mysqld_user, *mysqld_chroot;
static char *default_character_set_name;
......@@ -442,7 +443,7 @@ my_bool sp_automatic_privileges= 1;
ulong opt_binlog_rows_event_max_size;
const char *binlog_format_names[]= {"MIXED", "STATEMENT", "ROW", NullS};
#ifdef HAVE_INITGROUPS
static bool calling_initgroups= FALSE; /**< Used in SIGSEGV handler. */
volatile sig_atomic_t calling_initgroups= 0; /**< Used in SIGSEGV handler. */
#endif
uint mysqld_port, test_flags, select_errors, dropping_tables, ha_open_options;
uint mysqld_port_timeout;
......@@ -656,7 +657,9 @@ char *opt_logname, *opt_slow_logname, *opt_bin_logname;
/* Static variables */
static bool kill_in_progress, segfaulted;
static volatile sig_atomic_t kill_in_progress;
static my_bool opt_bootstrap, opt_myisam_log;
static int cleanup_done;
static ulong opt_specialflag;
......@@ -1703,9 +1706,9 @@ static void set_user(const char *user, struct passwd *user_info_arg)
calling_initgroups as a flag to the SIGSEGV handler that is then used to
output a specific message to help the user resolve this problem.
*/
calling_initgroups= TRUE;
calling_initgroups= 1;
initgroups((char*) user, user_info_arg->pw_gid);
calling_initgroups= FALSE;
calling_initgroups= 0;
#endif
if (setgid(user_info_arg->pw_gid) == -1)
{
......@@ -2335,7 +2338,7 @@ LONG WINAPI my_unhandler_exception_filter(EXCEPTION_POINTERS *ex_pointers)
__try
{
my_set_exception_pointers(ex_pointers);
handle_segfault(ex_pointers->ExceptionRecord->ExceptionCode);
handle_fatal_signal(ex_pointers->ExceptionRecord->ExceptionCode);
}
__except(EXCEPTION_EXECUTE_HANDLER)
{
......@@ -2409,161 +2412,6 @@ extern "C" char *my_demangle(const char *mangled_name, int *status)
#endif
extern "C" sig_handler handle_segfault(int sig)
{
time_t curr_time;
struct tm tm;
/*
Strictly speaking, one needs a mutex here
but since we have got SIGSEGV already, things are a mess
so not having the mutex is not as bad as possibly using a buggy
mutex - so we keep things simple
*/
if (segfaulted)
{
fprintf(stderr, "Fatal " SIGNAL_FMT " while backtracing\n", sig);
exit(1);
}
segfaulted = 1;
curr_time= my_time(0);
localtime_r(&curr_time, &tm);
fprintf(stderr,"\
%02d%02d%02d %2d:%02d:%02d - mysqld got " SIGNAL_FMT " ;\n\
This could be because you hit a bug. It is also possible that this binary\n\
or one of the libraries it was linked against is corrupt, improperly built,\n\
or misconfigured. This error can also be caused by malfunctioning hardware.\n",
tm.tm_year % 100, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec,
sig);
fprintf(stderr, "\
We will try our best to scrape up some info that will hopefully help diagnose\n\
the problem, but since we have already crashed, something is definitely wrong\n\
and this may fail.\n\n");
fprintf(stderr, "key_buffer_size=%lu\n",
(ulong) dflt_key_cache->key_cache_mem_size);
fprintf(stderr, "read_buffer_size=%ld\n", (long) global_system_variables.read_buff_size);
fprintf(stderr, "max_used_connections=%lu\n", max_used_connections);
fprintf(stderr, "max_threads=%u\n", thread_scheduler->max_threads);
fprintf(stderr, "thread_count=%u\n", thread_count);
fprintf(stderr, "connection_count=%u\n", connection_count);
fprintf(stderr, "It is possible that mysqld could use up to \n\
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = %lu K\n\
bytes of memory\n", ((ulong) dflt_key_cache->key_cache_mem_size +
(global_system_variables.read_buff_size +
global_system_variables.sortbuff_size) *
thread_scheduler->max_threads +
max_connections * sizeof(THD)) / 1024);
fprintf(stderr, "Hope that's ok; if not, decrease some variables in the equation.\n\n");
#if defined(HAVE_LINUXTHREADS)
if (sizeof(char*) == 4 && thread_count > UNSAFE_DEFAULT_LINUX_THREADS)
{
fprintf(stderr, "\
You seem to be running 32-bit Linux and have %d concurrent connections.\n\
If you have not changed STACK_SIZE in LinuxThreads and built the binary \n\
yourself, LinuxThreads is quite likely to steal a part of the global heap for\n\
the thread stack. Please read http://dev.mysql.com/doc/mysql/en/linux.html\n\n",
thread_count);
}
#endif /* HAVE_LINUXTHREADS */
#ifdef HAVE_STACKTRACE
THD *thd=current_thd;
if (!(test_flags & TEST_NO_STACKTRACE))
{
fprintf(stderr, "Thread pointer: 0x%lx\n", (long) thd);
fprintf(stderr, "Attempting backtrace. You can use the following "
"information to find out\nwhere mysqld died. If "
"you see no messages after this, something went\n"
"terribly wrong...\n");
my_print_stacktrace(thd ? (uchar*) thd->thread_stack : NULL,
my_thread_stack_size);
}
if (thd)
{
const char *kreason= "UNKNOWN";
switch (thd->killed) {
case THD::NOT_KILLED:
kreason= "NOT_KILLED";
break;
case THD::KILL_BAD_DATA:
kreason= "KILL_BAD_DATA";
break;
case THD::KILL_CONNECTION:
kreason= "KILL_CONNECTION";
break;
case THD::KILL_QUERY:
kreason= "KILL_QUERY";
break;
case THD::KILLED_NO_VALUE:
kreason= "KILLED_NO_VALUE";
break;
}
fprintf(stderr, "\nTrying to get some variables.\n"
"Some pointers may be invalid and cause the dump to abort.\n");
fprintf(stderr, "Query (%p): ", thd->query());
my_safe_print_str(thd->query(), min(1024, thd->query_length()));
fprintf(stderr, "Connection ID (thread ID): %lu\n", (ulong) thd->thread_id);
fprintf(stderr, "Status: %s\n", kreason);
fputc('\n', stderr);
}
fprintf(stderr, "\
The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains\n\
information that should help you find out what is causing the crash.\n");
fflush(stderr);
#endif /* HAVE_STACKTRACE */
#ifdef HAVE_INITGROUPS
if (calling_initgroups)
fprintf(stderr, "\n\
This crash occured while the server was calling initgroups(). This is\n\
often due to the use of a mysqld that is statically linked against glibc\n\
and configured to use LDAP in /etc/nsswitch.conf. You will need to either\n\
upgrade to a version of glibc that does not have this problem (2.3.4 or\n\
later when used with nscd), disable LDAP in your nsswitch.conf, or use a\n\
mysqld that is not statically linked.\n");
#endif
#ifdef HAVE_NPTL
if (thd_lib_detected == THD_LIB_LT && !getenv("LD_ASSUME_KERNEL"))
fprintf(stderr,"\n\
You are running a statically-linked LinuxThreads binary on an NPTL system.\n\
This can result in crashes on some distributions due to LT/NPTL conflicts.\n\
You should either build a dynamically-linked binary, or force LinuxThreads\n\
to be used with the LD_ASSUME_KERNEL environment variable. Please consult\n\
the documentation for your distribution on how to do that.\n");
#endif
if (locked_in_memory)
{
fprintf(stderr, "\n\
The \"--memlock\" argument, which was enabled, uses system calls that are\n\
unreliable and unstable on some operating systems and operating-system\n\
versions (notably, some versions of Linux). This crash could be due to use\n\
of those buggy OS calls. You should consider whether you really need the\n\
\"--memlock\" parameter and/or consult the OS distributer about \"mlockall\"\n\
bugs.\n");
}
#ifdef HAVE_WRITE_CORE
if (test_flags & TEST_CORE_ON_SIGNAL)
{
fprintf(stderr, "Writing a core file\n");
fflush(stderr);
my_write_core(sig);
}
#endif
#ifndef __WIN__
/* On Windows, do not terminate, but pass control to exception filter */
exit(1);
#endif
}
#if !defined(__WIN__)
#ifndef SA_RESETHAND
......@@ -2593,9 +2441,9 @@ static void init_signals(void)
my_init_stacktrace();
#endif
#if defined(__amiga__)
sa.sa_handler=(void(*)())handle_segfault;
sa.sa_handler=(void(*)())handle_fatal_signal;
#else
sa.sa_handler=handle_segfault;
sa.sa_handler=handle_fatal_signal;
#endif
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGABRT, &sa, NULL);
......@@ -4282,6 +4130,9 @@ int mysqld_main(int argc, char **argv)
to be able to read defaults files and parse options.
*/
my_progname= argv[0];
#ifdef HAVE_NPTL
ld_assume_kernel_is_set= (getenv("LD_ASSUME_KERNEL") != 0);
#endif
#ifndef _WIN32
// For windows, my_init() is called from the win specific mysqld_main
if (my_init()) // init my_sys library & pthreads
......@@ -6778,7 +6629,7 @@ static int mysql_init_variables(void)
opt_secure_auth= 0;
opt_bootstrap= opt_myisam_log= 0;
mqh_used= 0;
segfaulted= kill_in_progress= 0;
kill_in_progress= 0;
cleanup_done= 0;
server_id_supplied= 0;
test_flags= select_errors= dropping_tables= ha_open_options=0;
......
sql/set_var.h
View file @ b522a6ce
......@@ -34,6 +34,7 @@ class Item_func_set_user_var;
// This include needs to be here since item.h requires enum_var_type :-P
#include "item.h" /* Item */
#include "sql_class.h" /* THD */
extern TYPELIB bool_typelib;
......
sql/signal_handler.cc
View file @ b522a6ce
......@@ -16,7 +16,7 @@
#include "my_global.h"
#include <signal.h>
#include "mysql_priv.h"
#include "sys_vars.h"
#include "my_stacktrace.h"
#ifdef __WIN__
......@@ -111,7 +111,7 @@ extern "C" sig_handler handle_fatal_signal(int sig)
(ulong) max_used_connections);
my_safe_printf_stderr("max_threads=%u\n",
(uint) thread_scheduler.max_threads);
(uint) thread_scheduler->max_threads);
my_safe_printf_stderr("thread_count=%u\n", (uint) thread_count);
......@@ -124,7 +124,7 @@ extern "C" sig_handler handle_fatal_signal(int sig)
((ulong) dflt_key_cache->key_cache_mem_size +
(global_system_variables.read_buff_size +
global_system_variables.sortbuff_size) *
thread_scheduler.max_threads +
thread_scheduler->max_threads +
max_connections * sizeof(THD)) / 1024);
my_safe_printf_stderr("%s",
......
sql/sys_vars.cc
View file @ b522a6ce
......@@ -49,6 +49,8 @@
#include "../storage/perfschema/pfs_server.h"
#endif /* WITH_PERFSCHEMA_STORAGE_ENGINE */
TYPELIB bool_typelib={ array_elements(bool_values)-1, "", bool_values, 0 };
/*
This forward declaration is needed because including sql_base.h
causes further includes. [TODO] Eliminate this forward declaration
......@@ -56,6 +58,77 @@
*/
extern void close_thread_tables(THD *thd);
static bool update_buffer_size(THD *thd, KEY_CACHE *key_cache,
ptrdiff_t offset, ulonglong new_value)
{
bool error= false;
DBUG_ASSERT(offset == offsetof(KEY_CACHE, param_buff_size));
if (new_value == 0)
{
if (key_cache == dflt_key_cache)
{
my_error(ER_WARN_CANT_DROP_DEFAULT_KEYCACHE, MYF(0));
return true;
}
if (key_cache->key_cache_inited) // If initied
{
/*
Move tables using this key cache to the default key cache
and clear the old key cache.
*/
key_cache->in_init= 1;
mysql_mutex_unlock(&LOCK_global_system_variables);
key_cache->param_buff_size= 0;
ha_resize_key_cache(key_cache);
ha_change_key_cache(key_cache, dflt_key_cache);
/*
We don't delete the key cache as some running threads my still be in
the key cache code with a pointer to the deleted (empty) key cache
*/
mysql_mutex_lock(&LOCK_global_system_variables);
key_cache->in_init= 0;
}
return error;
}
key_cache->param_buff_size= new_value;
/* If key cache didn't exist initialize it, else resize it */
key_cache->in_init= 1;
mysql_mutex_unlock(&LOCK_global_system_variables);
if (!key_cache->key_cache_inited)
error= ha_init_key_cache(0, key_cache);
else
error= ha_resize_key_cache(key_cache);
mysql_mutex_lock(&LOCK_global_system_variables);
key_cache->in_init= 0;
return error;
}
static bool update_keycache_param(THD *thd, KEY_CACHE *key_cache,
ptrdiff_t offset, ulonglong new_value)
{
bool error= false;
DBUG_ASSERT(offset != offsetof(KEY_CACHE, param_buff_size));
keycache_var(key_cache, offset)= new_value;
key_cache->in_init= 1;
mysql_mutex_unlock(&LOCK_global_system_variables);
error= ha_resize_key_cache(key_cache);
mysql_mutex_lock(&LOCK_global_system_variables);
key_cache->in_init= 0;
return error;
}
/*
The rule for this file: everything should be 'static'. When a sys_var
variable or a function from this file is - in very rare cases - needed
......
sql/sys_vars.h
View file @ b522a6ce
......@@ -72,7 +72,6 @@
enum charset_enum {IN_SYSTEM_CHARSET, IN_FS_CHARSET};
static const char *bool_values[3]= {"OFF", "ON", 0};
TYPELIB bool_typelib={ array_elements(bool_values)-1, "", bool_values, 0 };
/**
A small wrapper class to pass getopt arguments as a pair
......@@ -710,76 +709,6 @@ class Sys_var_keycache: public Sys_var_ulonglong
}
};
static bool update_buffer_size(THD *thd, KEY_CACHE *key_cache,
ptrdiff_t offset, ulonglong new_value)
{
bool error= false;
DBUG_ASSERT(offset == offsetof(KEY_CACHE, param_buff_size));
if (new_value == 0)
{
if (key_cache == dflt_key_cache)
{
my_error(ER_WARN_CANT_DROP_DEFAULT_KEYCACHE, MYF(0));
return true;
}
if (key_cache->key_cache_inited) // If initied
{
/*
Move tables using this key cache to the default key cache
and clear the old key cache.
*/
key_cache->in_init= 1;
mysql_mutex_unlock(&LOCK_global_system_variables);
key_cache->param_buff_size= 0;
ha_resize_key_cache(key_cache);
ha_change_key_cache(key_cache, dflt_key_cache);
/*
We don't delete the key cache as some running threads my still be in
the key cache code with a pointer to the deleted (empty) key cache
*/
mysql_mutex_lock(&LOCK_global_system_variables);
key_cache->in_init= 0;
}
return error;
}
key_cache->param_buff_size= new_value;
/* If key cache didn't exist initialize it, else resize it */
key_cache->in_init= 1;
mysql_mutex_unlock(&LOCK_global_system_variables);
if (!key_cache->key_cache_inited)
error= ha_init_key_cache(0, key_cache);
else
error= ha_resize_key_cache(key_cache);
mysql_mutex_lock(&LOCK_global_system_variables);
key_cache->in_init= 0;
return error;
}
static bool update_keycache_param(THD *thd, KEY_CACHE *key_cache,
ptrdiff_t offset, ulonglong new_value)
{
bool error= false;
DBUG_ASSERT(offset != offsetof(KEY_CACHE, param_buff_size));
keycache_var(key_cache, offset)= new_value;
key_cache->in_init= 1;
mysql_mutex_unlock(&LOCK_global_system_variables);
error= ha_resize_key_cache(key_cache);
mysql_mutex_lock(&LOCK_global_system_variables);
key_cache->in_init= 0;
return error;
}
/**
The class for floating point variables
......
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