ID: 20467
Updated by: iliaa@php.net
Reported By: freddy77@angelfire.com
-Status: Open
+Status: Critical
Bug Type: Sybase (dblib) related
Operating System: Linux
PHP Version: 4.2.3
New Comment:
Someone familiar with the workings of the sybase extension should
definately review the patch and make the necessary corrections before
the next RC is out.
Previous Comments:
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[2002-11-18 13:25:50] freddy77@angelfire.com
I found also another problem.
If NULL is returned (length == 0) the loop
"while (*p == ' ') --p;"
can lead to a buffer underflow,
"while (p >= res_buf && *p == ' ') --p;"
fix the problem
freddy77
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[2002-11-17 13:34:54] freddy77@angelfire.com
I forgot. To check the issue try:
#!/home/freddy/install/bin/php -q
<?php
$db_handle = sybase_connect("server","user","pass");
sybase_select_db("tempdb", $db_handle);
$db_result = sybase_query("select convert(varbinary,space(120))");
$res = sybase_fetch_row($db_result);
print "\nres=$res[0]\n";
print sybase_num_rows($db_result);
$db_result = sybase_query("select convert(numeric(18,2),1234.89)");
$res = sybase_fetch_row($db_result);
print "\nres=$res[0]\n";
print sybase_num_rows($db_result);
?>
freddy77
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[2002-11-17 13:31:00] freddy77@angelfire.com
dbconvert convert binary -> char returning binary representation so
0x6789 (2 bytes) became '6789' (4 single byte characters)
When converting back to PHP (in ext/sybase/php_sybase_db.c) you pass
the same size buffer leading to a buffer overflow.
Following patch fix problem. It also fix another problem (it remove
last characters from conversion) and avoid future possible buffer
overflows due to strange types (like UNIQUEIDs in MSSQL)
diff -r -u10 php-4.2.3/ext/sybase/php_sybase_db.c
php-4.2.3mod/ext/sybase/php_sybase_db.c
--- php-4.2.3/ext/sybase/php_sybase_db.c Wed Mar 6 16:59:42 2002
+++ php-4.2.3mod/ext/sybase/php_sybase_db.c Sun Nov 17 20:08:31 2002
@@ -710,49 +710,51 @@
/*case SYBFLT8:*/
case SYBREAL: {
Z_DVAL_P(result) = (double) floatcol(offset);
Z_TYPE_P(result) = IS_DOUBLE;
break;
}
default: {
if (dbwillconvert(coltype(offset),SYBCHAR)) {
char *res_buf;
int res_length = dbdatlen(sybase_ptr->link,offset);
+ int src_length = res_length;
register char *p;
switch (coltype(offset)) {
case SYBBINARY:
case SYBVARBINARY:
+ res_length *= 2;
+ break;
case SYBCHAR:
case SYBVARCHAR:
case SYBTEXT:
case SYBIMAGE:
break;
default:
/* take no chances, no telling how big the result would really
be */
res_length += 20;
break;
}
res_buf = (char *) emalloc(res_length+1);
memset(res_buf,' ',res_length+1); /* XXX i'm sure there's a
better way
but i don't have sybase here to test
991105 thies@thieso.net */
- dbconvert(NULL,coltype(offset),dbdata(sybase_ptr->link,offset),
res_length,SYBCHAR,res_buf,-1);
+ dbconvert(NULL,coltype(offset),dbdata(sybase_ptr->link,offset),
src_length,SYBCHAR,res_buf,res_length);
/* get rid of trailing spaces */
p = res_buf + res_length;
- while (*p == ' ') {
+ while (*p == ' ')
p--;
- res_length--;
- }
*(++p) = 0; /* put a trailing NULL */
+ res_length = p - res_buf;
Z_STRLEN_P(result) = res_length;
Z_STRVAL_P(result) = res_buf;
Z_TYPE_P(result) = IS_STRING;
} else {
php_error(E_WARNING,"Sybase: column %d has unknown data type
(%d)", offset, coltype(offset));
ZVAL_FALSE(result);
}
}
}
Frediano Ziglio
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--
Edit this bug report at http://bugs.php.net/?id=20467&edit=1