fix use-after-free in ipaccess_bts_keepalive_fsm_alloc()
In ipaccess_bts_keepalive_fsm_alloc() we allocate a keepalive FSM
instance as a child of the respective struct ipa_client_conn, and
store the pointer to the respective struct e1inp_ts.
+ struct e1inp_line
|
---+ struct ipaccess_line (void *driver_data)
| |
| ---+ struct ipa_client_conn *ipa_cli[NUM_E1_TS] // <-- parent
|
---+ struct e1inp_ts ts[NUM_E1_TS]
| |
| ---+ .driver.ipaccess.ka_fsm // <-- pointer
When an ipaccess connection (be it OML or RSL) goes down and then
up again, for instance if the BSC gets restarted, osmo-bts crashes.
The problem is that struct ipa_client_conn gets free()ed before the
associated FSM instance gets terminated:
* e1inp_ipa_bts_rsl_connect_n() is called
** calling e1inp_ipa_bts_rsl_close_n()
*** this function free()s struct ipa_client_conn
*** (!) as well as the struct osmo_fsm_inst (talloc child)
** calling ipaccess_bts_keepalive_fsm_alloc()
*** calling ipaccess_keepalive_fsm_cleanup()
**** accessing free()d e1i_ts->driver.ipaccess.ka_fsm
**** BOOOM! segmentation fault
Fix this by calling ipaccess_keepalive_fsm_cleanup() before free()ing
the associated struct ipa_client_conn.
Note that ipaccess_bsc_keepalive_fsm_alloc() is not affected because
it's allocating keepalive FSMs using the global tall_ipa_ctx.
Change-Id: Ic56c4b5b7b24b63104908a0c24f2f645ba4c5c1b
Related: SYS#6438
diff --git a/src/input/ipaccess.c b/src/input/ipaccess.c
index 114389e..48a1d40 100644
--- a/src/input/ipaccess.c
+++ b/src/input/ipaccess.c
@@ -192,7 +192,7 @@
struct e1inp_line *line = e1i_ts->line;
struct osmo_fsm_inst *ka_fsm;
- ipaccess_keepalive_fsm_cleanup(e1i_ts);
+ OSMO_ASSERT(e1i_ts->driver.ipaccess.ka_fsm == NULL);
if (!line->ipa_kap)
return;
@@ -1208,6 +1208,7 @@
{
struct ipa_client_conn *conn;
struct ipaccess_line *il;
+ struct e1inp_ts *e1i_ts;
if (E1INP_SIGN_RSL+trx_nr-1 >= NUM_E1_TS) {
LOGP(DLINP, LOGL_ERROR,
@@ -1219,6 +1220,9 @@
if (!il)
return 0; /* Nothing to do, no lines created */
+ e1i_ts = e1inp_line_ipa_rsl_ts(line, trx_nr);
+ ipaccess_keepalive_fsm_cleanup(e1i_ts);
+
conn = il->ipa_cli[1 + trx_nr];
if (conn != NULL) {
ipa_client_conn_close(conn);