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gprs_ns2: add recursive anchor to protect against double free 

When free'ing a NSE/NSVC/BIND ensure there can't be a double
free by using a free anchor in the struct.

Recursive free's can happen when the NS user reacts on an event
(e.g. GPRS_NS2_AFF_CAUSE_VC_FAILURE) and calls the free().
Or when the user free's a NSVC when the NSE uses SNS as configuration,
the fsm tries to free it again.

Change-Id: If9823aadaa936e136aa43e88cee925ddd5974841
This commit is contained in:
Alexander Couzens 2021-07-19 03:40:02 +02:00 committed by laforge
parent 1c40525f44
commit 41589a3e7a
2 changed files with 20 additions and 5 deletions
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16
src/gb/gprs_ns2.c
View File

@ -639,9 +639,9 @@ err:
* \param[in] nsvc NS-VC to destroy */
void gprs_ns2_free_nsvc(struct gprs_ns2_vc *nsvc)
{
if (!nsvc)
if (!nsvc || nsvc->freed)
return;
nsvc->freed = true;
ns2_prim_status_ind(nsvc->nse, nsvc, 0, GPRS_NS2_AFF_CAUSE_VC_FAILURE);
llist_del(&nsvc->list);
@ -671,7 +671,7 @@ void gprs_ns2_free_nsvcs(struct gprs_ns2_nse *nse)
{
struct gprs_ns2_vc *nsvc, *tmp;
if (!nse)
if (!nse || nse->freed)
return;
llist_for_each_entry_safe(nsvc, tmp, &nse->nsvc, list) {
@ -889,9 +889,11 @@ uint16_t gprs_ns2_nse_nsei(struct gprs_ns2_nse *nse)
* \param[in] nse NS Entity to destroy */
void gprs_ns2_free_nse(struct gprs_ns2_nse *nse)
{
if (!nse)
struct gprs_ns2_vc *nsvc, *nsvc2;
if (!nse || nse->freed)
return;
nse->freed = true;
nse->alive = false;
if (nse->bss_sns_fi) {
osmo_fsm_inst_term(nse->bss_sns_fi, OSMO_FSM_TERM_REQUEST, NULL);
@ -901,6 +903,9 @@ void gprs_ns2_free_nse(struct gprs_ns2_nse *nse)
gprs_ns2_free_nsvcs(nse);
ns2_prim_status_ind(nse, NULL, 0, GPRS_NS2_AFF_CAUSE_FAILURE);
rate_ctr_group_free(nse->ctrg);
llist_for_each_entry_safe(nsvc, nsvc2, &nse->nsvc, list) {
gprs_ns2_free_nsvc(nsvc);
}
llist_del(&nse->list);
talloc_free(nse);
@ -1466,9 +1471,10 @@ void gprs_ns2_free_bind(struct gprs_ns2_vc_bind *bind)
{
struct gprs_ns2_vc *nsvc, *tmp;
struct gprs_ns2_nse *nse;
if (!bind)
if (!bind || bind->freed)
return;
bind->freed = true;
llist_for_each_entry_safe(nsvc, tmp, &bind->nsvc, blist) {
gprs_ns2_free_nsvc(nsvc);
}

9
src/gb/gprs_ns2_internal.h
View File

@ -215,6 +215,9 @@ struct gprs_ns2_nse {
/*! NSE-wide statistics */
struct rate_ctr_group *ctrg;
/*! recursive anchor */
bool freed;
};
/*! Structure representing a single NS-VC */
@ -259,6 +262,9 @@ struct gprs_ns2_vc {
enum gprs_ns2_vc_mode mode;
struct osmo_fsm_inst *fi;
/*! recursive anchor */
bool freed;
};
/*! Structure repesenting a bind instance. E.g. IPv4 listen port. */
@ -303,6 +309,9 @@ struct gprs_ns2_vc_bind {
uint8_t sns_data_weight;
struct osmo_stat_item_group *statg;
/*! recursive anchor */
bool freed;
};
struct gprs_ns2_vc_driver {