CVE-2026-98098: tipc: fix NULL deref in tipc_named_node_up() on empty publication list
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix NULL deref in tipcnamednodeup() on empty publication list
User-space applications can bind a large number of service addresses to one or more sockets. Each binding of a local-scope service address inserts one entry (publication) into the TIPC name table. If the number of these publications exceeds TIPCMAXPUBL (65535), protocol service types (such as node state and link state) are no longer inserted into the name table. This causes two issues:
1. User-space applications subscribing to node or link up/down events stop receiving notifications.
2. A NULL pointer dereference can occur:
BUG: kernel NULL pointer dereference, address: 00000000000000d0 ... CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.2.0-rc4-default+ #5 PREEMPT(full) ... RIP: 0010:tipcnamednodeup (./include/linux/skbuff.h:2251 net/tipc/namedistr.c:195 net/tipc/namedistr.c:221) ... Call Trace: <IRQ> tipcnodewriteunlock (net/tipc/node.c:428) tipcrcv (net/tipc/node.c:934 net/tipc/node.c:2189) tipcudprecv (net/tipc/udpmedia.c:389)
Thread 1 (tipcnetfinalize) | Thread 2 (nameddistribute) -----------------------------|----------------------------- | ... | listforeachentry(publ, pls, bindingnode) { | ... | skbqueuetail(list, skb); | ... | } | ... | hdr = bufmsg(skbpeektail(list)); ... | tipcnametblpublish(); |
If 'tipcnametblpublish()' (Thread 1) fails because the number of local publications reaches TIPCMAXPUBL, list (Thread 2) will be empty. As a result, NULL is passed to 'bufmsg()', leading to a NULL pointer dereference.
Fix these issues by allowing protocol service types (node state, link state, and topology server) to be inserted into the name table unconditionally. This ensures that users subscribing to these types always receive notifications. In addition, the maximum number of local user publications is reduced to (TIPCMAXPUBL - 1). This ensures that the maximum bulk size calculated in tipclinksetqueuelimits() remains valid.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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Fixed in 6.6.158.1-1 - Upgrade
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Event History
Frequently Asked Questions
Which systems are exposed to the crash condition?
Linux systems using TIPC are exposed when user-space applications create more than 65,535 local-scope service-address publications in the TIPC name table. The condition is associated with protocol service types no longer being inserted into that table.
What behavior may indicate that the publication limit has been exceeded?
Applications subscribed to TIPC node or link up/down events stop receiving those notifications. The system may also encounter a kernel NULL pointer dereference in tipc_named_node_up().
What can be done if the fix cannot be applied immediately?
Keep the number of local-scope service-address publications below TIPC_MAX_PUBL, which is 65,535. Avoid allowing applications to bind enough service addresses to exceed that limit.