* [PATCH net v6 1/3] tipc: fix NULL deref in tipc_named_node_up() on empty publication list
[not found] <20260717185701.2828080-1-bestswngs@gmail.com>
@ 2026-07-17 18:56 ` Weiming Shi
2026-07-17 18:56 ` [PATCH net v6 2/3] tipc: fix NULL deref in deferred bulk distribution on publish failure Weiming Shi
2026-07-17 18:57 ` [PATCH net v6 3/3] tipc: fix node reference leak when defer work is already pending Weiming Shi
2 siblings, 0 replies; 3+ messages in thread
From: Weiming Shi @ 2026-07-17 18:56 UTC (permalink / raw)
To: Jon Maloy, Tung Nguyen, netdev, tipc-discussion
Cc: Xiang Mei, Weiming Shi, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Simon Horman, kernel test robot,
Hoang Huu Le, linux-kernel
[The defer-to-workqueue approach is by Tung Nguyen, suggested by
Jon Maloy on the thread as the replacement for the item-less bulk
approach. Since the RFC only exists as an inline diff in the thread,
it is folded into this series so the fix is self-contained.]
named_distribute() stamps the last_bulk flag on the tail skb of the
publication list. When the list is empty no skb is enqueued and the
tail access dereferences NULL. tipc_named_node_up() hits this on an
empty cluster_scope, which happens with a node-id configuration where
cluster_scope is populated only later by tipc_net_finalize(). It is
reachable by an unprivileged user over a UDP bearer in a user+net
namespace. The reported crash:
KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]
RIP: 0010:tipc_named_node_up (net/tipc/name_distr.c:196)
tipc_named_node_up (net/tipc/name_distr.c:196 net/tipc/name_distr.c:221)
tipc_node_write_unlock (net/tipc/node.c:428)
tipc_rcv (net/tipc/node.c:2185)
tipc_udp_recv (net/tipc/udp_media.c:392)
Kernel panic - not syncing: Fatal exception in interrupt
When cluster_scope is empty at node-up, defer the bulk distribution
to a workqueue and wait for tipc_net_finalize() to publish the
node-state name, so named_distribute() always runs on a non-empty
list. On allocation failure, purge the partially built queue and
bring the link down so the bulk distribution restarts when the link
comes up again.
Fixes: cad2929dc432 ("tipc: update a binding service via broadcast")
Reported-by: Xiang Mei <xmei5@asu.edu>
Signed-off-by: Tung Nguyen <tung.quang.nguyen@est.tech>
Tested-by: Weiming Shi <bestswngs@gmail.com>
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
---
net/tipc/core.c | 1 +
net/tipc/core.h | 2 ++
net/tipc/name_distr.c | 48 +++++++++++++++++++++++++++++++++++++++----
net/tipc/name_distr.h | 3 ++-
net/tipc/net.c | 2 ++
net/tipc/node.c | 34 ++++++++++++++++++++++++++++--
6 files changed, 83 insertions(+), 7 deletions(-)
diff --git a/net/tipc/core.c b/net/tipc/core.c
index 434e70eabe08..ce164509d9e2 100644
--- a/net/tipc/core.c
+++ b/net/tipc/core.c
@@ -60,6 +60,7 @@ static int __net_init tipc_init_net(struct net *net)
tn->trial_addr = 0;
tn->addr_trial_end = 0;
tn->capabilities = TIPC_NODE_CAPABILITIES;
+ atomic_set(&tn->finalized, 0);
INIT_WORK(&tn->work, tipc_net_finalize_work);
memset(tn->node_id, 0, sizeof(tn->node_id));
memset(tn->node_id_string, 0, sizeof(tn->node_id_string));
diff --git a/net/tipc/core.h b/net/tipc/core.h
index 9ce5f9ff6cc0..76768844c808 100644
--- a/net/tipc/core.h
+++ b/net/tipc/core.h
@@ -145,6 +145,8 @@ struct tipc_net {
struct work_struct work;
/* The numbers of work queues in schedule */
atomic_t wq_count;
+ /* flag to indicate work has finished */
+ atomic_t finalized;
};
static inline struct tipc_net *tipc_net(struct net *net)
diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
index 190b49c5cbc3..b764274df758 100644
--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -147,7 +147,7 @@ struct sk_buff *tipc_named_withdraw(struct net *net, struct publication *p)
* @pls: linked list of publication items to be packed into buffer chain
* @seqno: sequence number for this message
*/
-static void named_distribute(struct net *net, struct sk_buff_head *list,
+static int named_distribute(struct net *net, struct sk_buff_head *list,
u32 dnode, struct list_head *pls, u16 seqno)
{
struct publication *publ;
@@ -164,8 +164,9 @@ static void named_distribute(struct net *net, struct sk_buff_head *list,
skb = named_prepare_buf(net, PUBLICATION, msg_rem,
dnode);
if (!skb) {
+ __skb_queue_purge(list);
pr_warn("Bulk publication failure\n");
- return;
+ return 1;
}
hdr = buf_msg(skb);
msg_set_bc_ack_invalid(hdr, true);
@@ -195,6 +196,8 @@ static void named_distribute(struct net *net, struct sk_buff_head *list,
hdr = buf_msg(skb_peek_tail(list));
msg_set_last_bulk(hdr);
msg_set_named_seqno(hdr, seqno);
+
+ return 0;
}
/**
@@ -203,7 +206,7 @@ static void named_distribute(struct net *net, struct sk_buff_head *list,
* @dnode: destination node
* @capabilities: peer node's capabilities
*/
-void tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities)
+int tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities)
{
struct name_table *nt = tipc_name_table(net);
struct tipc_net *tn = tipc_net(net);
@@ -218,9 +221,46 @@ void tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities)
spin_unlock_bh(&tn->nametbl_lock);
read_lock_bh(&nt->cluster_scope_lock);
- named_distribute(net, &head, dnode, &nt->cluster_scope, seqno);
+ /* tipc_net_finalize_work() has not finished inserting self address to
+ * name table yet.
+ */
+ if (unlikely(list_empty(&nt->cluster_scope))) {
+ read_unlock_bh(&nt->cluster_scope_lock);
+ return 1;
+ }
+
+ if (named_distribute(net, &head, dnode, &nt->cluster_scope, seqno)) {
+ read_unlock_bh(&nt->cluster_scope_lock);
+ return -ENOBUFS;
+ }
+
tipc_node_xmit(net, &head, dnode, 0);
read_unlock_bh(&nt->cluster_scope_lock);
+ return 0;
+}
+
+int tipc_named_dist_cluster_scope(struct net *net, u32 dnode)
+{
+ struct name_table *nt = tipc_name_table(net);
+ struct tipc_net *tn = tipc_net(net);
+ struct sk_buff_head head;
+ u16 seqno;
+
+ __skb_queue_head_init(&head);
+ wait_var_event(&tn->finalized, atomic_read(&tn->finalized));
+ spin_lock_bh(&tn->nametbl_lock);
+ seqno = nt->snd_nxt;
+ spin_unlock_bh(&tn->nametbl_lock);
+
+ read_lock_bh(&nt->cluster_scope_lock);
+ if (named_distribute(net, &head, dnode, &nt->cluster_scope, seqno)) {
+ read_unlock_bh(&nt->cluster_scope_lock);
+ return -ENOBUFS;
+ }
+ tipc_node_xmit(net, &head, dnode, 0);
+ read_unlock_bh(&nt->cluster_scope_lock);
+
+ return 0;
}
/**
diff --git a/net/tipc/name_distr.h b/net/tipc/name_distr.h
index c677f6f082df..cadf4e8c3e66 100644
--- a/net/tipc/name_distr.h
+++ b/net/tipc/name_distr.h
@@ -69,7 +69,8 @@ struct distr_item {
struct sk_buff *tipc_named_publish(struct net *net, struct publication *publ);
struct sk_buff *tipc_named_withdraw(struct net *net, struct publication *publ);
-void tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities);
+int tipc_named_node_up(struct net *net, u32 dnode, u16 capabilities);
+int tipc_named_dist_cluster_scope(struct net *net, u32 dnode);
void tipc_named_rcv(struct net *net, struct sk_buff_head *namedq,
u16 *rcv_nxt, bool *open);
void tipc_named_reinit(struct net *net);
diff --git a/net/tipc/net.c b/net/tipc/net.c
index 7e65d0b0c4a8..4c144e720ac1 100644
--- a/net/tipc/net.c
+++ b/net/tipc/net.c
@@ -139,6 +139,8 @@ static void tipc_net_finalize(struct net *net, u32 addr)
tipc_sk_reinit(net);
tipc_mon_reinit_self(net);
tipc_nametbl_publish(net, &ua, &sk, addr);
+ atomic_inc(&tn->finalized);
+ wake_up_var(&tn->finalized);
}
void tipc_net_finalize_work(struct work_struct *work)
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 97aa970a0d83..b545a47d6ccb 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -145,6 +145,8 @@ struct tipc_node {
#ifdef CONFIG_TIPC_CRYPTO
struct tipc_crypto *crypto_rx;
#endif
+ /* Work item for bulk distribution of cluster scope publications */
+ struct work_struct work;
};
/* Node FSM states and events:
@@ -303,6 +305,7 @@ static void tipc_node_free(struct rcu_head *rp)
#ifdef CONFIG_TIPC_CRYPTO
tipc_crypto_stop(&n->crypto_rx);
#endif
+ cancel_work_sync(&n->work);
kfree(n);
}
@@ -393,6 +396,19 @@ static void tipc_node_write_unlock_fast(struct tipc_node *n)
write_unlock_bh(&n->lock);
}
+static void tipc_node_dist_bulk(struct work_struct *work)
+{
+ struct tipc_node *node = container_of(work, struct tipc_node, work);
+
+ if (tipc_named_dist_cluster_scope(node->net, node->addr) < 0) {
+ u32 bearer_id = node->link_id & 0xffff;
+
+ tipc_node_link_down(node, bearer_id, false);
+ }
+
+ tipc_node_put(node);
+}
+
static void tipc_node_write_unlock(struct tipc_node *n)
__releases(n->lock)
{
@@ -424,8 +440,21 @@ static void tipc_node_write_unlock(struct tipc_node *n)
if (flags & TIPC_NOTIFY_NODE_DOWN)
tipc_publ_notify(net, publ_list, node, n->capabilities);
- if (flags & TIPC_NOTIFY_NODE_UP)
- tipc_named_node_up(net, node, n->capabilities);
+ if (flags & TIPC_NOTIFY_NODE_UP) {
+ int rc = 0;
+
+ rc = tipc_named_node_up(net, node, n->capabilities);
+ /* Defer bulk distribution to work queue */
+ if (rc > 0) {
+ tipc_node_get(n);
+ schedule_work(&n->work);
+ } else if (rc < 0) {
+ /* Bring the link down to start over bulk distribution
+ * when the link is up again.
+ */
+ tipc_node_link_down(n, bearer_id, false);
+ }
+ }
if (flags & TIPC_NOTIFY_LINK_UP) {
tipc_mon_peer_up(net, node, bearer_id);
@@ -564,6 +593,7 @@ struct tipc_node *tipc_node_create(struct net *net, u32 addr, u8 *peer_id,
INIT_LIST_HEAD(&n->list);
INIT_LIST_HEAD(&n->publ_list);
INIT_LIST_HEAD(&n->conn_sks);
+ INIT_WORK(&n->work, tipc_node_dist_bulk);
skb_queue_head_init(&n->bc_entry.namedq);
skb_queue_head_init(&n->bc_entry.inputq1);
__skb_queue_head_init(&n->bc_entry.arrvq);
--
2.43.0
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH net v6 2/3] tipc: fix NULL deref in deferred bulk distribution on publish failure
[not found] <20260717185701.2828080-1-bestswngs@gmail.com>
2026-07-17 18:56 ` [PATCH net v6 1/3] tipc: fix NULL deref in tipc_named_node_up() on empty publication list Weiming Shi
@ 2026-07-17 18:56 ` Weiming Shi
2026-07-17 18:57 ` [PATCH net v6 3/3] tipc: fix node reference leak when defer work is already pending Weiming Shi
2 siblings, 0 replies; 3+ messages in thread
From: Weiming Shi @ 2026-07-17 18:56 UTC (permalink / raw)
To: Jon Maloy, Tung Nguyen, netdev, tipc-discussion
Cc: Xiang Mei, Weiming Shi, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Simon Horman, Hoang Huu Le,
kernel test robot, linux-kernel
tipc_net_finalize() does not check the return value of
tipc_nametbl_publish(). If the publish fails, for example on a
GFP_ATOMIC allocation failure, the node state name never lands in
cluster_scope, but tn->finalized is still set. A worker deferred by
tipc_named_node_up() then wakes and calls named_distribute() with an
empty list. That replays the same unguarded buf_msg(skb_peek_tail(list))
tail stamp, this time on the tipc_node_dist_bulk workqueue:
KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
RIP: 0010:named_distribute (net/tipc/name_distr.c:200)
Workqueue: events tipc_node_dist_bulk
Call Trace:
tipc_named_dist_cluster_scope (net/tipc/name_distr.c:267)
tipc_node_dist_bulk (net/tipc/node.c:403)
process_one_work
worker_thread
Kernel panic - not syncing: Fatal exception in interrupt
Check the publish result and warn on failure, but still set finalized,
otherwise deferred workers would sleep forever. In
tipc_named_dist_cluster_scope() re-check cluster_scope after the wait
and skip the distribution when it is empty. This is a permanent
condition, so return 0 instead of an error, otherwise the link would
be bounced forever. Also guard the tail stamp in named_distribute()
itself, so a caller that misses the precondition gets a warning and a
link reset through the existing -ENOBUFS path instead of a crash.
Reproducing this needs an allocation failure during finalize, so I
verified it by stubbing out the publish call: both nodes log the
failure, the workers skip the distribution, no crash, no link flap.
The normal path is unchanged with the same two-node test.
Fixes: cad2929dc432 ("tipc: update a binding service via broadcast")
Reported-by: Xiang Mei <xmei5@asu.edu>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
---
net/tipc/name_distr.c | 11 +++++++++++
net/tipc/net.c | 3 ++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
index b764274df758..5b0fb09226fc 100644
--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -193,6 +193,10 @@ static int named_distribute(struct net *net, struct sk_buff_head *list,
skb_trim(skb, INT_H_SIZE + (msg_dsz - msg_rem));
__skb_queue_tail(list, skb);
}
+ if (skb_queue_empty(list)) {
+ pr_warn("Bulk publication list empty, nothing to distribute\n");
+ return 1;
+ }
hdr = buf_msg(skb_peek_tail(list));
msg_set_last_bulk(hdr);
msg_set_named_seqno(hdr, seqno);
@@ -253,6 +257,13 @@ int tipc_named_dist_cluster_scope(struct net *net, u32 dnode)
spin_unlock_bh(&tn->nametbl_lock);
read_lock_bh(&nt->cluster_scope_lock);
+ if (unlikely(list_empty(&nt->cluster_scope))) {
+ /* finalize is done but nothing was published (publish
+ * failed): a permanent state, nothing to synchronize.
+ */
+ read_unlock_bh(&nt->cluster_scope_lock);
+ return 0;
+ }
if (named_distribute(net, &head, dnode, &nt->cluster_scope, seqno)) {
read_unlock_bh(&nt->cluster_scope_lock);
return -ENOBUFS;
diff --git a/net/tipc/net.c b/net/tipc/net.c
index 4c144e720ac1..2aa8812c551a 100644
--- a/net/tipc/net.c
+++ b/net/tipc/net.c
@@ -138,7 +138,8 @@ static void tipc_net_finalize(struct net *net, u32 addr)
tipc_named_reinit(net);
tipc_sk_reinit(net);
tipc_mon_reinit_self(net);
- tipc_nametbl_publish(net, &ua, &sk, addr);
+ if (!tipc_nametbl_publish(net, &ua, &sk, addr))
+ pr_warn("Failed to publish own node state\n");
atomic_inc(&tn->finalized);
wake_up_var(&tn->finalized);
}
--
2.43.0
^ permalink raw reply [flat|nested] 3+ messages in thread