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BUG/MEDIUM: connection: Clear flags when a conn is removed from an idle list

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When a connection is removed from the safe list or the idle list,
CO_FL_SAFE_LIST and CO_FL_IDLE_LIST flags must be cleared. It is performed
when the connection is reused. But not when it is moved into the
toremove_conns list. It may be an issue because the multiplexer owning the
connection may be woken up before the connection is really removed. If the
connection flags are not sanitized, it may think the connection is idle and
reinsert it in the corresponding list. From this point, we can imagine
several bugs. An UAF or a connection reused with an invalid state for
instance.

To avoid any issue, the connection flags are sanitized when an idle
connection is moved into the toremove_conns list. The same is performed at
right places in the multiplexers. Especially because the connection release
may be delayed (for h2 and fcgi connections).

This patch shoudld fix the issue #2057. It must carefully be backported as
far as 2.2. Especially on the 2.2 where the code is really different. But
some conflicts should be expected on the 2.4 too.
This commit is contained in:
Christopher Faulet 2023-02-28 15:39:38 +01:00
parent 4bdd069637
commit 5e1b0e7bf8
4 changed files with 14 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/mux_fcgi.c
View File

@ -3140,8 +3140,10 @@ struct task *fcgi_timeout_task(struct task *t, void *context, unsigned int state
/* We're about to destroy the connection, so make sure nobody attempts
* to steal it from us.
*/
if (fconn->conn->flags & CO_FL_LIST_MASK)
if (fconn->conn->flags & CO_FL_LIST_MASK) {
conn_delete_from_tree(&fconn->conn->hash_node->node);
fconn->conn->flags &= ~CO_FL_LIST_MASK;
}
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}

4
src/mux_h1.c
View File

@ -3297,8 +3297,10 @@ struct task *h1_timeout_task(struct task *t, void *context, unsigned int state)
/* We're about to destroy the connection, so make sure nobody attempts
* to steal it from us.
*/
if (h1c->conn->flags & CO_FL_LIST_MASK)
if (h1c->conn->flags & CO_FL_LIST_MASK) {
conn_delete_from_tree(&h1c->conn->hash_node->node);
h1c->conn->flags &= ~CO_FL_LIST_MASK;
}
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}

7
src/mux_h2.c
View File

@ -4031,6 +4031,7 @@ static int h2_process(struct h2c *h2c)
if (conn->flags & CO_FL_LIST_MASK) {
HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
conn_delete_from_tree(&conn->hash_node->node);
conn->flags &= ~CO_FL_LIST_MASK;
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}
}
@ -4039,6 +4040,7 @@ static int h2_process(struct h2c *h2c)
if (conn->flags & CO_FL_LIST_MASK) {
HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
conn_delete_from_tree(&conn->hash_node->node);
conn->flags &= ~CO_FL_LIST_MASK;
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}
}
@ -4118,8 +4120,10 @@ struct task *h2_timeout_task(struct task *t, void *context, unsigned int state)
/* We're about to destroy the connection, so make sure nobody attempts
* to steal it from us.
*/
if (h2c->conn->flags & CO_FL_LIST_MASK)
if (h2c->conn->flags & CO_FL_LIST_MASK) {
conn_delete_from_tree(&h2c->conn->hash_node->node);
h2c->conn->flags &= ~CO_FL_LIST_MASK;
}
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}
@ -4172,6 +4176,7 @@ do_leave:
if (h2c->conn->flags & CO_FL_LIST_MASK) {
HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
conn_delete_from_tree(&h2c->conn->hash_node->node);
h2c->conn->flags &= ~CO_FL_LIST_MASK;
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}

2
src/server.c
View File

@ -5828,6 +5828,7 @@ static int srv_migrate_conns_to_remove(struct eb_root *idle_tree, struct mt_list
hash_node = ebmb_entry(node, struct conn_hash_node, node);
eb_delete(node);
hash_node->conn->flags &= ~CO_FL_LIST_MASK;
MT_LIST_APPEND(toremove_list, &hash_node->conn->toremove_list);
i++;
@ -5885,6 +5886,7 @@ void srv_release_conn(struct server *srv, struct connection *conn)
/* Remove the connection from any tree (safe, idle or available) */
HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
conn_delete_from_tree(&conn->hash_node->node);
conn->flags &= ~CO_FL_LIST_MASK;
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}