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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2026-74609

tipc: read le->link under the node lock in tipc_node_link_down()

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: tipc: read le->link under the node lock in tipc_node_link_down() tipc_node_link_down() caches the link pointer before taking n->lock: struct tipc_link *l = le->link; /* unlocked */ if (!l) return; tipc_node_write_lock(n); if (!tipc_link_is_establishing(l)) { /* deref l */ ... tipc_link_reset(l); /* write into l */ if (delete) { kfree(l); le->link = NULL; The delete=true caller frees that very object under n->lock, so the lock does not protect the cached pointer against it: - CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link supervision timer via tipc_node_timeout(), reads l unlocked and then dereferences it under n->lock; - CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable() -> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true) -> kfree(l). The link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers disable_media() only schedules the asynchronous cleanup_bearer() work, so its synchronize_net() runs after the links are already gone. An in-flight CPU A that has read l therefore dereferences freed memory once B frees it: a use-after-free read in tipc_link_is_establishing(), and a use-after-free write via tipc_link_reset() on the establishing branch. The following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6: BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285) Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0 tipc_link_is_establishing (net/tipc/link.c:285) tipc_node_link_down (net/tipc/node.c:1076) tipc_node_timeout (net/tipc/node.c:843) Allocated by task 9549: tipc_link_create (net/tipc/link.c:490) tipc_node_check_dest (net/tipc/node.c:1279) tipc_disc_rcv (net/tipc/discover.c:252) tipc_udp_recv (net/tipc/udp_media.c:389) Freed by task 9549: tipc_node_link_down (net/tipc/node.c:1084) tipc_node_delete_links (net/tipc/node.c:1320) bearer_disable (net/tipc/bearer.c:414) __tipc_nl_bearer_disable (net/tipc/bearer.c:992) Move the le->link read inside tipc_node_write_lock(), so it is serialised against the kfree() in the delete path. A racing teardown now either has not run yet, and we see a valid link, or has already run, and we see NULL.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 73f646cec35477b5099d7e952297cb9e1855be45 to < 2be741ad565c610871a6a95062c12c39da7168fdaffected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < 69d209461c110388710e483a130caf051e4fd09aaffected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < de017c22135f545ca4e65d1eada22887b64958ebaffected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < 47ba70891b10b2feb52462086b7fcd2ad75d3ce3affected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < a714d62513befef37f71f4ae89bb1fe173b65f2eaffected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < c3f2347a47754eac690967cfd82cb6d559817b07affected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < 5558a8312452ddb21eff22b1cbd84302ad951944affected
  • 73f646cec35477b5099d7e952297cb9e1855be45 to < cba9ccb47e9fa4cc77692fb896cc5ab57a667882affected

Linux Linux

Default version status: affected

  • 4.4affected
  • 0 to < 4.4unaffected
  • 5.10.265 to ≤ 5.10.*unaffected
  • 5.15.216 to ≤ 5.15.*unaffected
  • 6.1.183 to ≤ 6.1.*unaffected
  • 6.6.152 to ≤ 6.6.*unaffected
  • 6.12.104 to ≤ 6.12.*unaffected
  • 6.18.45 to ≤ 6.18.*unaffected
  • 7.1.9 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References