CVE-2022-49696
Published: 26 February 2025
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().
Security Summary
CVE-2022-49696 is a use-after-free vulnerability in the Linux kernel's Transparent Inter-Process Communication (TIPC) subsystem, specifically affecting the tipc_named_reinit function in net/tipc/name_distr.c. The issue stems from improper handling of the cancel_work_sync() function introduced in commit d966ddcc3821 ("tipc: fix a deadlock when flushing scheduled work"), which does not guarantee that the tipc_net_finalize_work is the last queued work before the TIPC namespace is destroyed via tipc_exit_net(). This can lead to access of a destroyed TIPC instance when the work attempts to enqueue later. The vulnerability was identified by syzbot on kernel version 5.18.0-rc4-syzkaller and carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), mapped to CWE-416.
A local attacker with low privileges can exploit this vulnerability by triggering conditions that lead to the use-after-free during TIPC namespace finalization in a workqueue context, such as via the events workqueue processing tipc_net_finalize_work. Successful exploitation could result in high-impact confidentiality, integrity, and availability violations, potentially allowing arbitrary code execution, data corruption, or kernel crashes, as indicated by the KASAN-reported read of size 8 at a freed address.
Kernel stable patches address the issue by re-ordering the cancel_work_sync() call to ensure tipc_net_finalize_work is the last queued work and is fully completed before namespace destruction. Relevant commits include 361c5521c1e4 (stable), 8b246ddd394d, 911600bf5a5e, and cd7789e659e8, available via git.kernel.org. Security practitioners should update affected Linux kernels to incorporate these fixes.
Details
- CWE(s)