On Mon, 2008-03-10 at 06:37 +0000, Nigel Kukard wrote:
> Might be a good idea to identify exactly which versions of MySQL are
> affected, as far as I can determine this is a MySQL issue and not a
> Policyd issue. ie. Doing a query and aborting it or having it timeout
> should also nuke the results for that query, not return them in a
> subsequent query. No harm in adding a work-around though.
I'm running mysql 5.0.51a, and the bug is present.
I wrote a simple C program to test it. You will need to compile and run
it on your policyd database server. For me, it outputs:
Long query returned 7662499
Long query returned -1
Short query returned 7662499
Short query returned 1
but it should output:
Long query returned 7662499
Long query returned -1
Short query returned 1
Short query returned 1
If the second "Long query" doesn't return -1, you will need to adjust
the long query to something that takes longer than 1 second on your
server.
Dan
/* Change MYSQLUSER and MYSQLPASS to match your info, then complie
with something like:
gcc -I/usr/local/include/mysql -L/usr/local/lib/mysql -lmysqlclient -o illustrate_bug illustrate_bug.c
*/
#include <stdio.h>
#include <stdlib.h>
#include <mysql.h>
#include <sys/signal.h>
#include <setjmp.h>
#define MYSQLUSER "postfix"
#define MYSQLPASS "p0stf1x"
MYSQL *mysql;
sigjmp_buf sjmp;
int run_long_query(int);
int run_short_query(void);
void sigalrm_handler(void);
main ()
{
mysql=mysql_init(NULL);
mysql_real_connect(mysql, "127.0.0.1", MYSQLUSER, MYSQLPASS, "policyd", 3306, NULL, 0);
int count;
count=run_long_query(0);
printf("Long query returned %d\n", count);
count=run_long_query(1);
printf("Long query returned %d\n", count);
count=run_short_query();
printf("Short query returned %d\n", count);
count=run_short_query();
printf("Short query returned %d\n", count);
}
int run_long_query(int timeout)
{
if( sigsetjmp (sjmp, 1) ){
alarm (0);
signal (SIGALRM, SIG_DFL);
return(-1);
}
signal (SIGALRM, (void *) sigalrm_handler);
alarm(timeout);
mysql_query(mysql, "SELECT COUNT(*) from triplet where _count=1");
alarm (0);
signal (SIGALRM, SIG_DFL);
MYSQL_RES *res=mysql_store_result(mysql);
MYSQL_ROW row=mysql_fetch_row(res);
int count=atoi(*row);
return count;
}
int run_short_query()
{
mysql_query(mysql, "SELECT COUNT(*) from whitelist where _whitelist='127.0.0.1'");
MYSQL_RES *res=mysql_store_result(mysql);
if( ! res ){ return 0; }
MYSQL_ROW row=mysql_fetch_row(res);
int count=atoi(*row);
return count;
}
void sigalrm_handler (void)
{
alarm (0); /* reset alarm timer */
siglongjmp (sjmp, 1); /* jump back */
}
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