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From:Martin Hansson Date:December 30 2010 9:19am
Subject:bzr commit into mysql-5.1-bugteam branch (martin.hansson:3537) Bug#58165
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#At file:///data0/martin/bzrroot/bug58165/5.1bt-lazy_copy/ based on revid:dao-gang.qu@stripped

 3537 Martin Hansson	2010-12-30
      Bug#58165: "my_empty_string" gets modified and causes LOAD DATA to fail and
      other crashes
      
      Some string manipulating SQL functions use a shared string object intended to
      contain an immutable empty string. This object was used by the SQL function
      SUBSTRING_INDEX() to return an empty string when one argument was of the wrong
      datatype. If the string object was then modified by the sql function INSERT(),
      undefined behavior ensued.
      
      Fixed by instead modifying the string object representing the function's
      result value whenever string manipulating SQL functions return an empty
      string.
      
      Relevant code has also been documented.

    modified:
      mysql-test/r/func_str.result
      mysql-test/t/func_str.test
      sql/item_strfunc.cc
      sql/item_strfunc.h
      sql/sql_string.cc
      sql/sql_string.h
=== modified file 'mysql-test/r/func_str.result'
--- a/mysql-test/r/func_str.result	2010-12-14 16:08:25 +0000
+++ b/mysql-test/r/func_str.result	2010-12-30 09:19:40 +0000
@@ -2612,4 +2612,20 @@ CONVERT(('' IN (REVERSE(CAST(('') AS DEC
 1
 Warnings:
 Warning	1292	Truncated incorrect DECIMAL value: ''
+# 
+# Bug#58165: "my_empty_string" gets modified and causes LOAD DATA to fail
+# and other crashes
+#
+CREATE TABLE t1 ( a TEXT );
+SELECT 'aaaaaaaaaaaaaa' INTO OUTFILE 'bug58165.txt';
+SELECT insert( substring_index( 'a', 'a', 'b' ), 1, 0, 'x' );
+insert( substring_index( 'a', 'a', 'b' ), 1, 0, 'x' )
+x
+Warnings:
+Warning	1292	Truncated incorrect INTEGER value: 'b'
+LOAD DATA INFILE 'bug58165.txt' INTO TABLE t1;
+SELECT * FROM t1;
+a
+aaaaaaaaaaaaaa
+DROP TABLE t1;
 End of 5.1 tests

=== modified file 'mysql-test/t/func_str.test'
--- a/mysql-test/t/func_str.test	2010-12-14 16:08:25 +0000
+++ b/mysql-test/t/func_str.test	2010-12-30 09:19:40 +0000
@@ -1369,4 +1369,15 @@ DROP TABLE t1;
 SELECT '1' IN ('1', SUBSTRING(-9223372036854775809, 1));
 SELECT CONVERT(('' IN (REVERSE(CAST(('') AS DECIMAL)), '')), CHAR(3));
 
+--echo # 
+--echo # Bug#58165: "my_empty_string" gets modified and causes LOAD DATA to fail
+--echo # and other crashes
+--echo #
+CREATE TABLE t1 ( a TEXT );
+SELECT 'aaaaaaaaaaaaaa' INTO OUTFILE 'bug58165.txt';
+SELECT insert( substring_index( 'a', 'a', 'b' ), 1, 0, 'x' );
+LOAD DATA INFILE 'bug58165.txt' INTO TABLE t1;
+SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo End of 5.1 tests

=== modified file 'sql/item_strfunc.cc'
--- a/sql/item_strfunc.cc	2010-11-11 10:25:23 +0000
+++ b/sql/item_strfunc.cc	2010-12-30 09:19:40 +0000
@@ -39,6 +39,9 @@ C_MODE_START
 #include "../mysys/my_static.h"			// For soundex_map
 C_MODE_END
 
+/**
+   @todo Remove this. It is not safe to use a shared String object.
+ */
 String my_empty_string("",default_charset_info);
 
 
@@ -461,7 +464,7 @@ String *Item_func_des_encrypt::val_str(S
   if ((null_value= args[0]->null_value))
     return 0;                                   // ENCRYPT(NULL) == NULL
   if ((res_length=res->length()) == 0)
-    return &my_empty_string;
+    return make_empty_result();
 
   if (arg_count == 1)
   {
@@ -652,7 +655,7 @@ String *Item_func_concat_ws::val_str(Str
     }
 
   if (i ==  arg_count)
-    return &my_empty_string;
+    return make_empty_result();
 
   for (i++; i < arg_count ; i++)
   {
@@ -803,7 +806,7 @@ String *Item_func_reverse::val_str(Strin
     return 0;
   /* An empty string is a special case as the string pointer may be null */
   if (!res->length())
-    return &my_empty_string;
+    return make_empty_result();
   if (tmp_value.alloced_length() < res->length() &&
       tmp_value.realloc(res->length()))
   {
@@ -1143,8 +1146,7 @@ String *Item_func_left::val_str(String *
 
   /* if "unsigned_flag" is set, we have a *huge* positive number. */
   if ((length <= 0) && (!args[1]->unsigned_flag))
-    return &my_empty_string;
-
+    return make_empty_result();
   if ((res->length() <= (ulonglong) length) ||
       (res->length() <= (char_pos= res->charpos((int) length))))
     return res;
@@ -1187,7 +1189,7 @@ String *Item_func_right::val_str(String 
 
   /* if "unsigned_flag" is set, we have a *huge* positive number. */
   if ((length <= 0) && (!args[1]->unsigned_flag))
-    return &my_empty_string; /* purecov: inspected */
+    return make_empty_result(); /* purecov: inspected */
 
   if (res->length() <= (ulonglong) length)
     return res; /* purecov: inspected */
@@ -1226,7 +1228,7 @@ String *Item_func_substr::val_str(String
   /* Negative or zero length, will return empty string. */
   if ((arg_count == 3) && (length <= 0) && 
       (length == 0 || !args[2]->unsigned_flag))
-    return &my_empty_string;
+    return make_empty_result();
 
   /* Assumes that the maximum length of a String is < INT_MAX32. */
   /* Set here so that rest of code sees out-of-bound value as such. */
@@ -1237,12 +1239,12 @@ String *Item_func_substr::val_str(String
   /* Assumes that the maximum length of a String is < INT_MAX32. */
   if ((!args[1]->unsigned_flag && (start < INT_MIN32 || start > INT_MAX32)) ||
       (args[1]->unsigned_flag && ((ulonglong) start > INT_MAX32)))
-    return &my_empty_string;
+    return make_empty_result();
 
   start= ((start < 0) ? res->numchars() + start : start - 1);
   start= res->charpos((int) start);
   if ((start < 0) || ((uint) start + 1 > res->length()))
-    return &my_empty_string;
+    return make_empty_result();
 
   length= res->charpos((int) length, (uint32) start);
   tmp_length= res->length() - start;
@@ -1305,7 +1307,7 @@ String *Item_func_substr_index::val_str(
   null_value=0;
   uint delimiter_length= delimiter->length();
   if (!res->length() || !delimiter_length || !count)
-    return &my_empty_string;		// Wrong parameters
+    return make_empty_result();		// Wrong parameters
 
   res->set_charset(collation.collation);
 
@@ -1654,7 +1656,7 @@ String *Item_func_password::val_str(Stri
   if ((null_value=args[0]->null_value))
     return 0;
   if (res->length() == 0)
-    return &my_empty_string;
+    return make_empty_result();
   my_make_scrambled_password(tmp_value, res->ptr(), res->length());
   str->set(tmp_value, SCRAMBLED_PASSWORD_CHAR_LENGTH, res->charset());
   return str;
@@ -1678,7 +1680,7 @@ String *Item_func_old_password::val_str(
   if ((null_value=args[0]->null_value))
     return 0;
   if (res->length() == 0)
-    return &my_empty_string;
+    return make_empty_result();
   my_make_scrambled_password_323(tmp_value, res->ptr(), res->length());
   str->set(tmp_value, SCRAMBLED_PASSWORD_CHAR_LENGTH_323, res->charset());
   return str;
@@ -1706,8 +1708,7 @@ String *Item_func_encrypt::val_str(Strin
   if ((null_value=args[0]->null_value))
     return 0;
   if (res->length() == 0)
-    return &my_empty_string;
-
+    return make_empty_result();
   if (arg_count == 1)
   {					// generate random salt
     time_t timestamp=current_thd->query_start();
@@ -1967,7 +1968,7 @@ String *Item_func_soundex::val_str(Strin
   for ( ; ; ) /* Skip pre-space */
   {
     if ((rc= cs->cset->mb_wc(cs, &wc, (uchar*) from, (uchar*) end)) <= 0)
-      return &my_empty_string; /* EOL or invalid byte sequence */
+      return make_empty_result(); /* EOL or invalid byte sequence */
     
     if (rc == 1 && cs->ctype)
     {
@@ -1992,7 +1993,7 @@ String *Item_func_soundex::val_str(Strin
         {
           /* Extra safety - should not really happen */
           DBUG_ASSERT(false);
-          return &my_empty_string;
+          return make_empty_result();
         }
         to+= rc;
         break;
@@ -2289,7 +2290,7 @@ String *Item_func_make_set::val_str(Stri
 	  else
 	  {
 	    if (tmp_str.copy(*res))		// Don't use 'str'
-	      return &my_empty_string;
+              return make_empty_result();
 	    result= &tmp_str;
 	  }
 	}
@@ -2299,11 +2300,11 @@ String *Item_func_make_set::val_str(Stri
 	  {					// Copy data to tmp_str
 	    if (tmp_str.alloc(result->length()+res->length()+1) ||
 		tmp_str.copy(*result))
-	      return &my_empty_string;
+              return make_empty_result();
 	    result= &tmp_str;
 	  }
 	  if (tmp_str.append(STRING_WITH_LEN(","), &my_charset_bin) || tmp_str.append(*res))
-	    return &my_empty_string;
+            return make_empty_result();
 	}
       }
     }
@@ -2442,7 +2443,7 @@ String *Item_func_repeat::val_str(String
   null_value= 0;
 
   if (count <= 0 && (count == 0 || !args[1]->unsigned_flag))
-    return &my_empty_string;
+    return make_empty_result();
 
   /* Assumes that the maximum length of a String is < INT_MAX32. */
   /* Bounds check on count:  If this is triggered, we will error. */
@@ -2750,7 +2751,7 @@ String *Item_func_conv::val_str(String *
 
   ptr= longlong2str(dec, ans, to_base);
   if (str->copy(ans, (uint32) (ptr-ans), default_charset()))
-    return &my_empty_string;
+    return make_empty_result();
   return str;
 }
 
@@ -2917,7 +2918,7 @@ String *Item_func_hex::val_str(String *s
       return 0;
     ptr= longlong2str(dec,ans,16);
     if (str->copy(ans,(uint32) (ptr-ans),default_charset()))
-      return &my_empty_string;			// End of memory
+      return make_empty_result();			// End of memory
     return str;
   }
 

=== modified file 'sql/item_strfunc.h'
--- a/sql/item_strfunc.h	2010-03-29 13:42:49 +0000
+++ b/sql/item_strfunc.h	2010-12-30 09:19:40 +0000
@@ -22,6 +22,16 @@
 
 class Item_str_func :public Item_func
 {
+protected:
+  /**
+     Sets the result value of the function an empty string, using the current
+     character set. No memory is allocated.
+     @retval A pointer to the str_value member.
+   */
+  String *make_empty_result() {
+    str_value.set("", 0, collation.collation);
+    return &str_value; 
+  }
 public:
   Item_str_func() :Item_func() { decimals=NOT_FIXED_DEC; }
   Item_str_func(Item *a) :Item_func(a) {decimals=NOT_FIXED_DEC; }

=== modified file 'sql/sql_string.cc'
--- a/sql/sql_string.cc	2010-07-09 12:00:17 +0000
+++ b/sql/sql_string.cc	2010-12-30 09:19:40 +0000
@@ -58,11 +58,33 @@ bool String::real_alloc(uint32 arg_lengt
 }
 
 
-/*
-** Check that string is big enough. Set string[alloc_length] to 0
-** (for C functions)
-*/
+/**
+   Allocates a new buffer on the heap for this String.
+
+   - If the String's internal buffer is privately owned and heap allocated,
+     one of the following is performed.
+
+     - If the requested length is greater than what fits in the buffer, a new
+       buffer is allocated, data moved and the old buffer freed.
+
+     - If the requested length is less or equal to what fits in the buffer, a
+       null character is inserted at the appropriate position.
 
+   - If the String does not keep a private buffer on the heap, such a buffer
+     will be allocated and the string copied accoring to its length, as found
+     in String::length().
+ 
+   For C compatibility, the new string buffer is null terminated.
+
+   @param alloc_length The requested string size in characters, excluding any
+   null terminator.
+
+   @retval false Either the copy operation is complete or, if the size of the
+   new buffer is smaller than the currently allocated buffer (if one exists),
+   no allocation occured.
+
+   @retval true An error occured when attempting to allocate memory.
+*/
 bool String::realloc(uint32 alloc_length)
 {
   uint32 len=ALIGN_SIZE(alloc_length+1);
@@ -196,6 +218,17 @@ bool String::copy()
   return FALSE;
 }
 
+/**
+   Copies the internal buffer from str. If this String has a private heap
+   allocated buffer where new data does not fit, a new buffer is allocated
+   before copying and the old buffer freed. Character set information is also
+   copied.
+   
+   @param str The string whose internal buffer is to be copied.
+   
+   @retval false Success.
+   @retval true Memory allocation failed.
+*/
 bool String::copy(const String &str)
 {
   if (alloc(str.str_length))

=== modified file 'sql/sql_string.h'
--- a/sql/sql_string.h	2010-10-19 22:36:59 +0000
+++ b/sql/sql_string.h	2010-12-30 09:19:40 +0000
@@ -136,6 +136,16 @@ public:
       Alloced_length=0;
     str_charset=str.str_charset;
   }
+
+
+  /**
+     Points the internal buffer to the supplied one. The old buffer is freed.
+     @param str Pointer to the new buffer.
+     @param arg_length Length of the new buffer in characters, excluding any 
+            null character.
+     @param cs Character set to use for interpreting string data.
+     @note The new buffer will not be null terminated.
+  */
   inline void set(char *str,uint32 arg_length, CHARSET_INFO *cs)
   {
     free();


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bzr commit into mysql-5.1-bugteam branch (martin.hansson:3537) Bug#58165Martin Hansson30 Dec