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authorJon Maloy <jon.maloy@ericsson.com>2018-04-11 22:52:09 +0200
committerDavid S. Miller <davem@davemloft.net>2018-04-12 21:46:10 -0400
commitc3317f4db831b7564ff8d1670326456a7fbbbcb3 (patch)
tree845a5dd46e764b071f8dedcf56233457ad10121b /net/tipc
parent1c2734b31d72316e3faaad88c0c9c46fa92a4b20 (diff)
downloadlinux-c3317f4db831b7564ff8d1670326456a7fbbbcb3.tar.bz2
tipc: fix unbalanced reference counter
When a topology subscription is created, we may encounter (or KASAN may provoke) a failure to create a corresponding service instance in the binding table. Instead of letting the tipc_nametbl_subscribe() report the failure back to the caller, the function just makes a warning printout and returns, without incrementing the subscription reference counter as expected by the caller. This makes the caller believe that the subscription was successful, so it will at a later moment try to unsubscribe the item. This involves a sub_put() call. Since the reference counter never was incremented in the first place, we get a premature delete of the subscription item, followed by a "use-after-free" warning. We fix this by adding a return value to tipc_nametbl_subscribe() and make the caller aware of the failure to subscribe. This bug seems to always have been around, but this fix only applies back to the commit shown below. Given the low risk of this happening we believe this to be sufficient. Fixes: commit 218527fe27ad ("tipc: replace name table service range array with rb tree") Reported-by: syzbot+aa245f26d42b8305d157@syzkaller.appspotmail.com Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
-rw-r--r--net/tipc/name_table.c5
-rw-r--r--net/tipc/name_table.h2
-rw-r--r--net/tipc/subscr.c5
3 files changed, 9 insertions, 3 deletions
diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c
index b1fe20972aa9..4068eaad61a6 100644
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -665,13 +665,14 @@ int tipc_nametbl_withdraw(struct net *net, u32 type, u32 lower,
/**
* tipc_nametbl_subscribe - add a subscription object to the name table
*/
-void tipc_nametbl_subscribe(struct tipc_subscription *sub)
+bool tipc_nametbl_subscribe(struct tipc_subscription *sub)
{
struct name_table *nt = tipc_name_table(sub->net);
struct tipc_net *tn = tipc_net(sub->net);
struct tipc_subscr *s = &sub->evt.s;
u32 type = tipc_sub_read(s, seq.type);
struct tipc_service *sc;
+ bool res = true;
spin_lock_bh(&tn->nametbl_lock);
sc = tipc_service_find(sub->net, type);
@@ -685,8 +686,10 @@ void tipc_nametbl_subscribe(struct tipc_subscription *sub)
pr_warn("Failed to subscribe for {%u,%u,%u}\n", type,
tipc_sub_read(s, seq.lower),
tipc_sub_read(s, seq.upper));
+ res = false;
}
spin_unlock_bh(&tn->nametbl_lock);
+ return res;
}
/**
diff --git a/net/tipc/name_table.h b/net/tipc/name_table.h
index 4b14fc28d9e2..0febba41da86 100644
--- a/net/tipc/name_table.h
+++ b/net/tipc/name_table.h
@@ -126,7 +126,7 @@ struct publication *tipc_nametbl_insert_publ(struct net *net, u32 type,
struct publication *tipc_nametbl_remove_publ(struct net *net, u32 type,
u32 lower, u32 upper,
u32 node, u32 key);
-void tipc_nametbl_subscribe(struct tipc_subscription *s);
+bool tipc_nametbl_subscribe(struct tipc_subscription *s);
void tipc_nametbl_unsubscribe(struct tipc_subscription *s);
int tipc_nametbl_init(struct net *net);
void tipc_nametbl_stop(struct net *net);
diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index b7d80bc5f4ab..f340e53da625 100644
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -153,7 +153,10 @@ struct tipc_subscription *tipc_sub_subscribe(struct net *net,
memcpy(&sub->evt.s, s, sizeof(*s));
spin_lock_init(&sub->lock);
kref_init(&sub->kref);
- tipc_nametbl_subscribe(sub);
+ if (!tipc_nametbl_subscribe(sub)) {
+ kfree(sub);
+ return NULL;
+ }
timer_setup(&sub->timer, tipc_sub_timeout, 0);
timeout = tipc_sub_read(&sub->evt.s, timeout);
if (timeout != TIPC_WAIT_FOREVER)