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.

mysys/stacktrace.c

@@ -52,10 +52,11 @@ void my_init_stacktrace()
 
 static void print_buffer(char *buffer, size_t count)
 {
+  const char s[]= " ";
   for (; count && *buffer; --count)
   {
-    int c= (int) *buffer++;
-    fputc(isprint(c) ? c : ' ', stderr);
+    my_write_stderr(isprint(*buffer) ? buffer : s, 1);
+    ++buffer;
   }
 }
 
@@ -119,10 +120,10 @@ static int safe_print_str(const char *addr, int max_len)
 
   /* Output a new line if something was printed. */
   if (total != (size_t) max_len)
-    fputc('\n', stderr);
+    my_safe_printf_stderr("%s", "\n");
 
   if (nbytes == -1)
-    fprintf(stderr, "Can't read from address %p: %m.\n", addr);
+    my_safe_printf_stderr("Can't read from address %p\n", addr);
 
   close(fd);
 
@@ -144,13 +145,13 @@ void my_safe_print_str(const char* val, int max_len)
 
   if (!PTR_SANE(val))
   {
-    fprintf(stderr, "is an invalid pointer\n");
+    my_safe_printf_stderr("%s", "is an invalid pointer\n");
     return;
   }
 
   for (; max_len && PTR_SANE(val) && *val; --max_len)
-    fputc(*val++, stderr);
-  fputc('\n', stderr);
+    my_write_stderr((val++), 1);
+  my_safe_printf_stderr("%s", "\n");
 }
 
 #if defined(HAVE_PRINTSTACK)
@@ -162,14 +163,15 @@ void my_print_stacktrace(uchar* stack_bottom __attribute__((unused)),
                          ulong thread_stack __attribute__((unused)))
 {
   if (printstack(fileno(stderr)) == -1)
-    fprintf(stderr, "Error when traversing the stack, stack appears corrupt.\n");
+    my_safe_printf_stderr("%s",
+      "Error when traversing the stack, stack appears corrupt.\n");
   else
-    fprintf(stderr,
-            "Please read "
-            "http://dev.mysql.com/doc/refman/5.1/en/resolve-stack-dump.html\n"
-            "and follow instructions on how to resolve the stack trace.\n"
-            "Resolved stack trace is much more helpful in diagnosing the\n"
-            "problem, so please do resolve it\n");
+    my_safe_printf_stderr("%s"
+      "Please read "
+      "http://dev.mysql.com/doc/refman/5.1/en/resolve-stack-dump.html\n"
+      "and follow instructions on how to resolve the stack trace.\n"
+      "Resolved stack trace is much more helpful in diagnosing the\n"
+      "problem, so please do resolve it\n");
 }
 
 #elif HAVE_BACKTRACE && (HAVE_BACKTRACE_SYMBOLS || HAVE_BACKTRACE_SYMBOLS_FD)
@@ -207,9 +209,9 @@ static void my_demangle_symbols(char **addrs, int n)
     }
 
     if (demangled)
-      fprintf(stderr, "%s(%s+%s\n", addrs[i], demangled, end);
+      my_safe_printf_stderr("%s(%s+%s\n", addrs[i], demangled, end);
     else
-      fprintf(stderr, "%s\n", addrs[i]);
+      my_safe_printf_stderr("%s\n", addrs[i]);
   }
 }
 
@@ -220,8 +222,8 @@ void my_print_stacktrace(uchar* stack_bottom, ulong thread_stack)
   void *addrs[128];
   char **strings= NULL;
   int n = backtrace(addrs, array_elements(addrs));
-  fprintf(stderr, "stack_bottom = %p thread_stack 0x%lx\n",
-          stack_bottom, thread_stack);
+  my_safe_printf_stderr("stack_bottom = %p thread_stack 0x%lx\n",
+                        stack_bottom, thread_stack);
 #if BACKTRACE_DEMANGLE
   if ((strings= backtrace_symbols(addrs, n)))
   {
@@ -314,8 +316,9 @@ void my_print_stacktrace(uchar* stack_bottom, ulong thread_stack)
 #endif
   if (!fp)
   {
-    fprintf(stderr, "frame pointer is NULL, did you compile with\n\
--fomit-frame-pointer? Aborting backtrace!\n");
+    my_safe_printf_stderr("%s",
+      "frame pointer is NULL, did you compile with\n"
+      "-fomit-frame-pointer? Aborting backtrace!\n");
     return;
   }
 
@@ -323,24 +326,28 @@ void my_print_stacktrace(uchar* stack_bottom, ulong thread_stack)
   {
     ulong tmp= min(0x10000,thread_stack);
     /* Assume that the stack starts at the previous even 65K */
-    stack_bottom= (uchar*) (((ulong) &fp + tmp) &
-			  ~(ulong) 0xFFFF);
-    fprintf(stderr, "Cannot determine thread, fp=%p, backtrace may not be correct.\n", fp);
+    stack_bottom= (uchar*) (((ulong) &fp + tmp) & ~(ulong) 0xFFFF);
+    my_safe_printf_stderr("Cannot determine thread, fp=%p, "
+                          "backtrace may not be correct.\n", fp);
   }
   if (fp > (uchar**) stack_bottom ||
       fp < (uchar**) stack_bottom - thread_stack)
   {
-    fprintf(stderr, "Bogus stack limit or frame pointer,\
- fp=%p, stack_bottom=%p, thread_stack=%ld, aborting backtrace.\n",
-	    fp, stack_bottom, thread_stack);
+    my_safe_printf_stderr("Bogus stack limit or frame pointer, "
+                          "fp=%p, stack_bottom=%p, thread_stack=%ld, "
+                          "aborting backtrace.\n",
+                          fp, stack_bottom, thread_stack);
     return;
   }
 
-  fprintf(stderr, "Stack range sanity check OK, backtrace follows:\n");
+  my_safe_printf_stderr("%s",
+    "Stack range sanity check OK, backtrace follows:\n");
 #if defined(__alpha__) && defined(__GNUC__)
-  fprintf(stderr, "Warning: Alpha stacks are difficult -\
- will be taking some wild guesses, stack trace may be incorrect or \
- terminate abruptly\n");
+  my_safe_printf_stderr("%s",
+    "Warning: Alpha stacks are difficult -"
+    "will be taking some wild guesses, stack trace may be incorrect or "
+    "terminate abruptly\n");
+
   /* On Alpha, we need to get pc */
   __asm __volatile__ ("bsr %0, do_next; do_next: "
 		      :"=r"(pc)
@@ -354,8 +361,9 @@ void my_print_stacktrace(uchar* stack_bottom, ulong thread_stack)
   {
 #if defined(__i386__) || defined(__x86_64__)
     uchar** new_fp = (uchar**)*fp;
-    fprintf(stderr, "%p\n", frame_count == sigreturn_frame_count ?
-	    *(fp + SIGRETURN_FRAME_OFFSET) : *(fp + 1));
+    my_safe_printf_stderr("%p\n",
+                          frame_count == sigreturn_frame_count ?
+                          *(fp + SIGRETURN_FRAME_OFFSET) : *(fp + 1));
 #endif /* defined(__386__)  || defined(__x86_64__) */
 
 #if defined(__alpha__) && defined(__GNUC__)
@@ -369,38 +377,40 @@ void my_print_stacktrace(uchar* stack_bottom, ulong thread_stack)
     {
       pc = find_prev_pc(pc, fp);
       if (pc)
-	fprintf(stderr, "%p\n", pc);
+	my_safe_printf_stderr("%p\n", pc);
       else
       {
-	fprintf(stderr, "Not smart enough to deal with the rest\
- of this stack\n");
+        my_safe_printf_stderr("%s",
+          "Not smart enough to deal with the rest of this stack\n");
 	goto end;
       }
     }
     else
     {
-      fprintf(stderr, "Not smart enough to deal with the rest of this stack\n");
+      my_safe_printf_stderr("%s",
+        "Not smart enough to deal with the rest of this stack\n");
       goto end;
     }
 #endif /* defined(__alpha__) && defined(__GNUC__) */
     if (new_fp <= fp )
     {
-      fprintf(stderr, "New value of fp=%p failed sanity check,\
- terminating stack trace!\n", new_fp);
+      my_safe_printf_stderr("New value of fp=%p failed sanity check, "
+                            "terminating stack trace!\n", new_fp);
       goto end;
     }
     fp = new_fp;
     ++frame_count;
   }
-
-  fprintf(stderr, "Stack trace seems successful - bottom reached\n");
+  my_safe_printf_stderr("%s",
+                        "Stack trace seems successful - bottom reached\n");
 
 end:
-  fprintf(stderr,
-          "Please read http://dev.mysql.com/doc/refman/5.1/en/resolve-stack-dump.html\n"
-          "and follow instructions on how to resolve the stack trace.\n"
-          "Resolved stack trace is much more helpful in diagnosing the\n"
-          "problem, so please do resolve it\n");
+  my_safe_printf_stderr("%s",
+    "Please read "
+    "http://dev.mysql.com/doc/refman/5.1/en/resolve-stack-dump.html\n"
+    "and follow instructions on how to resolve the stack trace.\n"
+    "Resolved stack trace is much more helpful in diagnosing the\n"
+    "problem, so please do resolve it\n");
 }
 #endif /* TARGET_OS_LINUX */
 #endif /* HAVE_STACKTRACE */
@@ -618,7 +628,7 @@ void my_print_stacktrace(uchar* unused1, ulong unused2)
       &(package.sym));
     have_source= SymGetLineFromAddr64(hProcess, addr, &line_offset, &line);
 
-    fprintf(stderr, "%p    ", addr);
+    my_safe_printf_stderr("%p    ", addr);
     if(have_module)
     {
       char *base_image_name= strrchr(module.ImageName, '\\');
@@ -626,12 +636,13 @@ void my_print_stacktrace(uchar* unused1, ulong unused2)
         base_image_name++;
       else
         base_image_name= module.ImageName;
-      fprintf(stderr, "%s!", base_image_name);
+      my_safe_printf_stderr("%s!", base_image_name);
     }
     if(have_symbol)
-      fprintf(stderr, "%s()", package.sym.Name);
+      my_safe_printf_stderr("%s()", package.sym.Name);
+
     else if(have_module)
-      fprintf(stderr, "???");
+      my_safe_printf_stderr("%s", "???");
 
     if(have_source)
     {
@@ -640,11 +651,11 @@ void my_print_stacktrace(uchar* unused1, ulong unused2)
         base_file_name++;
       else
         base_file_name= line.FileName;
-      fprintf(stderr,"[%s:%u]", base_file_name, line.LineNumber);
+      my_safe_printf_stderr("[%s:%u]",
+                            base_file_name, line.LineNumber);
     }
-    fprintf(stderr, "\n");
+    my_safe_printf_stderr("%s", "\n");
   }
-  fflush(stderr);
 }
 
 
@@ -681,22 +692,22 @@ void my_write_core(int unused)
     if(MiniDumpWriteDump(GetCurrentProcess(), GetCurrentProcessId(),
       hFile, MiniDumpNormal, &info, 0, 0))
     {
-      fprintf(stderr, "Minidump written to %s\n",
-        _fullpath(path, dump_fname, sizeof(path)) ? path : dump_fname);
+      my_safe_printf_stderr("Minidump written to %s\n",
+                            _fullpath(path, dump_fname, sizeof(path)) ?
+                            path : dump_fname);
     }
     else
     {
-      fprintf(stderr,"MiniDumpWriteDump() failed, last error %u\n",
-        GetLastError());
+      my_safe_printf_stderr("MiniDumpWriteDump() failed, last error %u\n",
+                            (uint) GetLastError());
     }
     CloseHandle(hFile);
   }
   else
   {
-    fprintf(stderr, "CreateFile(%s) failed, last error %u\n", dump_fname,
-      GetLastError());
+    my_safe_printf_stderr("CreateFile(%s) failed, last error %u\n",
+                          dump_fname, (uint) GetLastError());
   }
-  fflush(stderr);
 }
 
 
@@ -704,11 +715,212 @@ void my_safe_print_str(const char *val, int len)
 {
   __try
   {
-    fprintf(stderr, "%.*s\n", len, val);
+    my_write_stderr(val, len);
   }
   __except(EXCEPTION_EXECUTE_HANDLER)
   {
-    fprintf(stderr, "is an invalid string pointer\n");
+    my_safe_printf_stderr("%s", "is an invalid string pointer\n");
   }
 }
 #endif /*__WIN__*/
+
+
+#ifdef __WIN__
+size_t my_write_stderr(const void *buf, size_t count)
+{
+  DWORD bytes_written;
+  SetFilePointer(GetStdHandle(STD_ERROR_HANDLE), 0, NULL, FILE_END);
+  WriteFile(GetStdHandle(STD_ERROR_HANDLE), buf, count, &bytes_written, NULL);
+  return bytes_written;
+}
+#else
+size_t my_write_stderr(const void *buf, size_t count)
+{
+  return (size_t) write(STDERR_FILENO, buf, count);
+}
+#endif
+
+
+static const char digits[]= "0123456789abcdef";
+
+char *my_safe_utoa(int base, ulonglong val, char *buf)
+{
+  *buf--= 0;
+  do {
+    *buf--= digits[val % base];
+  } while ((val /= base) != 0);
+  return buf + 1;
+}
+
+
+char *my_safe_itoa(int base, longlong val, char *buf)
+{
+  char *orig_buf= buf;
+  const my_bool is_neg= (val < 0);
+  *buf--= 0;
+
+  if (is_neg)
+    val= -val;
+  if (is_neg && base == 16)
+  {
+    int ix;
+    val-= 1;
+    for (ix= 0; ix < 16; ++ix)
+      buf[-ix]= '0';
+  }
+  
+  do {
+    *buf--= digits[val % base];
+  } while ((val /= base) != 0);
+
+  if (is_neg && base == 10)
+    *buf--= '-';
+
+  if (is_neg && base == 16)
+  {
+    int ix;
+    buf= orig_buf - 1;
+    for (ix= 0; ix < 16; ++ix, --buf)
+    {
+      switch (*buf)
+      {
+      case '0': *buf= 'f'; break;
+      case '1': *buf= 'e'; break;
+      case '2': *buf= 'd'; break;
+      case '3': *buf= 'c'; break;
+      case '4': *buf= 'b'; break;
+      case '5': *buf= 'a'; break;
+      case '6': *buf= '9'; break;
+      case '7': *buf= '8'; break;
+      case '8': *buf= '7'; break;
+      case '9': *buf= '6'; break;
+      case 'a': *buf= '5'; break;
+      case 'b': *buf= '4'; break;
+      case 'c': *buf= '3'; break;
+      case 'd': *buf= '2'; break;
+      case 'e': *buf= '1'; break;
+      case 'f': *buf= '0'; break;
+      }
+    }
+  }
+  return buf+1;
+}
+
+
+static const char *check_longlong(const char *fmt, my_bool *have_longlong)
+{
+  *have_longlong= FALSE;
+  if (*fmt == 'l')
+  {
+    fmt++;
+    if (*fmt != 'l')
+      *have_longlong= (sizeof(long) == sizeof(longlong));
+    else
+    {
+      fmt++;
+      *have_longlong= TRUE;
+    }
+  }
+  return fmt;
+}
+
+static size_t my_safe_vsnprintf(char *to, size_t size,
+                                const char* format, va_list ap)
+{
+  char *start= to;
+  char *end= start + size - 1;
+  for (; *format; ++format)
+  {
+    my_bool have_longlong = FALSE;
+    if (*format != '%')
+    {
+      if (to == end)                            /* end of buffer */
+        break;
+      *to++= *format;                           /* copy ordinary char */
+      continue;
+    }
+    ++format;                                   /* skip '%' */
+
+    format= check_longlong(format, &have_longlong);
+
+    switch (*format)
+    {
+    case 'd':
+    case 'i':
+    case 'u':
+    case 'x':
+    case 'p':
+      {
+        longlong ival= 0;
+        ulonglong uval = 0;
+        if (*format == 'p')
+          have_longlong= (sizeof(void *) == sizeof(longlong));
+        if (have_longlong)
+        {
+          if (*format == 'u')
+            uval= va_arg(ap, ulonglong);
+          else
+            ival= va_arg(ap, longlong);
+        }
+        else
+        {
+          if (*format == 'u')
+            uval= va_arg(ap, unsigned int);
+          else
+            ival= va_arg(ap, int);
+        }
+
+        {
+          char buff[22];
+          const int base= (*format == 'x' || *format == 'p') ? 16 : 10;
+          char *val_as_str= (*format == 'u') ?
+            my_safe_utoa(base, uval, &buff[sizeof(buff)-1]) :
+            my_safe_itoa(base, ival, &buff[sizeof(buff)-1]);
+
+          /* Strip off "ffffffff" if we have 'x' format without 'll' */
+          if (*format == 'x' && !have_longlong && ival < 0)
+            val_as_str+= 8;
+
+          while (*val_as_str && to < end)
+            *to++= *val_as_str++;
+          continue;
+        }
+      }
+    case 's':
+      {
+        const char *val= va_arg(ap, char*);
+        if (!val)
+          val= "(null)";
+        while (*val && to < end)
+          *to++= *val++;
+        continue;
+      }
+    }
+  }
+  *to= 0;
+  return to - start;
+}
+
+
+size_t my_safe_snprintf(char* to, size_t n, const char* fmt, ...)
+{
+  size_t result;
+  va_list args;
+  va_start(args,fmt);
+  result= my_safe_vsnprintf(to, n, fmt, args);
+  va_end(args);
+  return result;
+}
+
+
+size_t my_safe_printf_stderr(const char* fmt, ...)
+{
+  char to[512];
+  size_t result;
+  va_list args;
+  va_start(args,fmt);
+  result= my_safe_vsnprintf(to, sizeof(to), fmt, args);
+  va_end(args);
+  my_write_stderr(to, result);
+  return result;
+}