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Babel: Seqno requests are properly decoupled from neighbors when the underlying interface disappears

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When an interface disappears, all the neighbors are freed as well. Seqno
requests were anyway not decoupled from them, leading to strange
segfaults. This fix adds a proper seqno request list inside neighbors to
make sure that no pointer to neighbor is kept after free.
This commit is contained in:
Maria Matejka 2021-05-30 13:07:16 +02:00
parent 10498b8e89
commit ebd5751cde
3 changed files with 22 additions and 13 deletions
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2
lib/lists.h
View file

@ -59,6 +59,8 @@ typedef union list { /* In fact two overlayed nodes */
/* WALK_LIST_FIRST supposes that called code removes each processed node */ /* WALK_LIST_FIRST supposes that called code removes each processed node */
#define WALK_LIST_FIRST(n,list) \ #define WALK_LIST_FIRST(n,list) \
while(n=HEAD(list), (NODE (n))->next) while(n=HEAD(list), (NODE (n))->next)
#define WALK_LIST_FIRST2(n,pos,list) \
while(n=SKIP_BACK(typeof(*n),pos,HEAD(list)), (n)->pos.next)
#define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \ #define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \
n=(void *)((NODE (n))->prev)) n=(void *)((NODE (n))->prev))
#define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \ #define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \

30
proto/babel/babel.c
View file

@ -56,13 +56,6 @@ static void babel_update_cost(struct babel_neighbor *n);
static inline void babel_kick_timer(struct babel_proto *p); static inline void babel_kick_timer(struct babel_proto *p);
static inline void babel_iface_kick_timer(struct babel_iface *ifa); static inline void babel_iface_kick_timer(struct babel_iface *ifa);
static inline void babel_lock_neighbor(struct babel_neighbor *nbr)
{ if (nbr) nbr->uc++; }
static inline void babel_unlock_neighbor(struct babel_neighbor *nbr)
{ if (nbr && !--nbr->uc) mb_free(nbr); }
/* /*
* Functions to maintain data structures * Functions to maintain data structures
*/ */
@ -316,8 +309,9 @@ babel_add_seqno_request(struct babel_proto *p, struct babel_entry *e,
return; return;
/* Found older */ /* Found older */
babel_unlock_neighbor(sr->nbr);
rem_node(NODE sr); rem_node(NODE sr);
rem_node(&sr->nbr_node);
goto found; goto found;
} }
@ -330,7 +324,10 @@ found:
sr->hop_count = hop_count; sr->hop_count = hop_count;
sr->count = 0; sr->count = 0;
sr->expires = current_time() + BABEL_SEQNO_REQUEST_EXPIRY; sr->expires = current_time() + BABEL_SEQNO_REQUEST_EXPIRY;
babel_lock_neighbor(sr->nbr = nbr);
if (sr->nbr = nbr)
add_tail(&nbr->requests, &sr->nbr_node);
add_tail(&e->requests, NODE sr); add_tail(&e->requests, NODE sr);
babel_send_seqno_request(p, e, sr); babel_send_seqno_request(p, e, sr);
@ -339,7 +336,9 @@ found:
static void static void
babel_remove_seqno_request(struct babel_proto *p, struct babel_seqno_request *sr) babel_remove_seqno_request(struct babel_proto *p, struct babel_seqno_request *sr)
{ {
babel_unlock_neighbor(sr->nbr); if (sr->nbr)
rem_node(&sr->nbr_node);
rem_node(NODE sr); rem_node(NODE sr);
sl_free(p->seqno_slab, sr); sl_free(p->seqno_slab, sr);
} }
@ -427,7 +426,7 @@ babel_get_neighbor(struct babel_iface *ifa, ip_addr addr)
nbr->txcost = BABEL_INFINITY; nbr->txcost = BABEL_INFINITY;
nbr->cost = BABEL_INFINITY; nbr->cost = BABEL_INFINITY;
init_list(&nbr->routes); init_list(&nbr->routes);
babel_lock_neighbor(nbr); init_list(&nbr->requests);
add_tail(&ifa->neigh_list, NODE nbr); add_tail(&ifa->neigh_list, NODE nbr);
return nbr; return nbr;
@ -448,9 +447,16 @@ babel_flush_neighbor(struct babel_proto *p, struct babel_neighbor *nbr)
babel_flush_route(p, r); babel_flush_route(p, r);
} }
struct babel_seqno_request *sr;
WALK_LIST_FIRST2(sr, nbr_node, nbr->requests)
{
sr->nbr = NULL;
rem_node(&sr->nbr_node);
}
nbr->ifa = NULL; nbr->ifa = NULL;
rem_node(NODE nbr); rem_node(NODE nbr);
babel_unlock_neighbor(nbr); mb_free(nbr);
} }
static void static void

3
proto/babel/babel.h
View file

@ -198,7 +198,6 @@ struct babel_neighbor {
struct babel_iface *ifa; struct babel_iface *ifa;
ip_addr addr; ip_addr addr;
uint uc; /* Reference counter for seqno requests */
u16 rxcost; /* Sent in last IHU */ u16 rxcost; /* Sent in last IHU */
u16 txcost; /* Received in last IHU */ u16 txcost; /* Received in last IHU */
u16 cost; /* Computed neighbor cost */ u16 cost; /* Computed neighbor cost */
@ -212,6 +211,7 @@ struct babel_neighbor {
btime ihu_expiry; btime ihu_expiry;
list routes; /* Routes this neighbour has sent us (struct babel_route) */ list routes; /* Routes this neighbour has sent us (struct babel_route) */
list requests; /* Seqno requests bound to this neighbor */
}; };
struct babel_source { struct babel_source {
@ -241,6 +241,7 @@ struct babel_route {
struct babel_seqno_request { struct babel_seqno_request {
node n; node n;
node nbr_node;
u64 router_id; u64 router_id;
u16 seqno; u16 seqno;
u8 hop_count; u8 hop_count;