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Fix error handling with threads on OOM in ECPG connection logic 

An out-of-memory failure happening when allocating the structures to
store the connection parameter keywords and values would mess up with
the set of connections saved, as on failure the pthread mutex would
still be hold with the new connection object listed but free()'d.

Rather than just unlocking the mutex, which would leave the static list
of connections into an inconsistent state, move the allocation for the
structures of the connection parameters before beginning the test
manipulation.  This ensures that the list of connections and the
connection mutex remain consistent all the time in this code path.

This error is unlikely going to happen, but this could mess up badly
with ECPG clients in surprising ways, so backpatch all the way down.

Reported-by: ryancaicse
Discussion: https://postgr.es/m/17186-b4cfd8f0eb4d1dee@postgresql.org
Backpatch-through: 9.6
This commit is contained in:
Michael Paquier 2021-09-13 13:23:50 +09:00
parent fee1040fe3
commit fa703b317e
1 changed files with 41 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

75
src/interfaces/ecpg/ecpglib/connect.c
View File

@ -458,6 +458,47 @@ ECPGconnect(int lineno, int c, const char *name, const char *user, const char *p
else
realname = NULL;
/*
* Count options for the allocation done below (this may produce an
* overestimate, it's ok).
*/
if (options)
for (i = 0; options[i]; i++)
if (options[i] == '=')
connect_params++;
if (user && strlen(user) > 0)
connect_params++;
if (passwd && strlen(passwd) > 0)
connect_params++;
/*
* Allocate enough space for all connection parameters. These allocations
* are done before manipulating the list of connections to ease the error
* handling on failure.
*/
conn_keywords = (const char **) ecpg_alloc((connect_params + 1) * sizeof(char *), lineno);
conn_values = (const char **) ecpg_alloc(connect_params * sizeof(char *), lineno);
if (conn_keywords == NULL || conn_values == NULL)
{
if (host)
ecpg_free(host);
if (port)
ecpg_free(port);
if (options)
ecpg_free(options);
if (realname)
ecpg_free(realname);
if (dbname)
ecpg_free(dbname);
if (conn_keywords)
ecpg_free(conn_keywords);
if (conn_values)
ecpg_free(conn_values);
free(this);
return false;
}
/* add connection to our list */
#ifdef ENABLE_THREAD_SAFETY
pthread_mutex_lock(&connections_mutex);
@ -488,40 +529,6 @@ ECPGconnect(int lineno, int c, const char *name, const char *user, const char *p
options ? "with options " : "", options ? options : "",
(user && strlen(user) > 0) ? "for user " : "", user ? user : "");
/* count options (this may produce an overestimate, it's ok) */
if (options)
for (i = 0; options[i]; i++)
if (options[i] == '=')
connect_params++;
if (user && strlen(user) > 0)
connect_params++;
if (passwd && strlen(passwd) > 0)
connect_params++;
/* allocate enough space for all connection parameters */
conn_keywords = (const char **) ecpg_alloc((connect_params + 1) * sizeof(char *), lineno);
conn_values = (const char **) ecpg_alloc(connect_params * sizeof(char *), lineno);
if (conn_keywords == NULL || conn_values == NULL)
{
if (host)
ecpg_free(host);
if (port)
ecpg_free(port);
if (options)
ecpg_free(options);
if (realname)
ecpg_free(realname);
if (dbname)
ecpg_free(dbname);
if (conn_keywords)
ecpg_free(conn_keywords);
if (conn_values)
ecpg_free(conn_values);
free(this);
return false;
}
i = 0;
if (realname)
{