CVE-2022-49696: tipc: fix use-after-free Read in tipc_named_reinit

Vulnerability summary

CVE-2022-49696 is a high (CVSS 7.8) Use After Free vulnerability in linux. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 21.3% of scored vulnerabilities.

Timeline

1. 26-02-2025
   PublishedVulnerability first disclosed.
2. 05-08-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: tipc: fix use-after-free Read in tipc_named_reinit syzbot found the following issue on: ================================================================== BUG: KASAN: use-after-free in tipc_named_reinit+0x94f/0x9b0 net/tipc/name_distr.c:413 Read of size 8 at addr ffff88805299a000 by task kworker/1:9/23764 CPU: 1 PID: 23764 Comm: kworker/1:9 Not tainted 5.18.0-rc4-syzkaller-00878-g17d49e6e8012 #0 Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events tipc_net_finalize_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 tipc_named_reinit+0x94f/0x9b0 net/tipc/name_distr.c:413 tipc_net_finalize+0x234/0x3d0 net/tipc/net.c:138 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 </TASK> [...] ================================================================== In the commit d966ddcc3821 ("tipc: fix a deadlock when flushing scheduled work"), the cancel_work_sync() function just to make sure ONLY the work tipc_net_finalize_work() is executing/pending on any CPU completed before tipc namespace is destroyed through tipc_exit_net(). But this function is not guaranteed the work is the last queued. So, the destroyed instance may be accessed in the work which will try to enqueue later. In order to completely fix, we re-order the calling of cancel_work_sync() to make sure the work tipc_net_finalize_work() was last queued and it must be completed by calling cancel_work_sync().

• CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.