Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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2.1
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None
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None
Description
When a mysql connection is created and is set to not blocking, mysql_close() doesn't free the memory associate with async causing a severe memory leak.
Depending from the the speed of your CPU and your available memory, the follow code can eat all available memory in just few seconds:
#include <mysql.h>
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#include <stdio.h>
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int main() {
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while(1) {
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MYSQL *mysql=mysql_init(NULL);
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mysql_options(mysql, MYSQL_OPT_NONBLOCK, 0); // this line triggers the bug
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mysql_close(mysql);
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}
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return 0;
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}
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Attachments
Activity
| Field | Original Value | New Value |
|---|---|---|
| Fix Version/s | 3.0.0 [ 18700 ] | |
| Fix Version/s | 2.2.0 [ 19500 ] | |
| Resolution | Fixed [ 1 ] | |
| Status | Open [ 1 ] | Closed [ 6 ] |
Because non blocking API is implemented using coroutine, it is possible that the stack is freed while being used by another function. This will lead to invalid read/write on memory already freed.
I think this is a better patch:
@@ -2192,6 +2192,16 @@
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my_free(mysql->options.extension->ssl_crlpath, MYF(MY_ALLOW_ZERO_PTR));
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if(hash_inited(&mysql->options.extension->connect_attrs))
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hash_free(&mysql->options.extension->connect_attrs);
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+ {
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+ struct mysql_async_context *ctxt;
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+ if ((ctxt = mysql->options.extension->async_context) != 0) {
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+ if (ctxt->active==0) {
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+ my_context_destroy(&ctxt->async_context);
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+ my_free((gptr)ctxt, MYF(0));
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+ mysql->options.extension->async_context=NULL;
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+ }
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+ }
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+ }
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}
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my_free((gptr)mysql->options.extension, MYF(MY_ALLOW_ZERO_PTR));
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/* clear all pointer */
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| Workflow | MariaDB connectors [ 69912 ] | MariaDB v4 [ 160991 ] |
Quick patch in mysql_close_options() :
2194a2195,2202> {> struct mysql_async_context *ctxt;> if ((ctxt = mysql->options.extension->async_context) != 0)> {> my_context_destroy(&ctxt->async_context);> my_free((gptr)ctxt, MYF(0));> }> }