CVE-2025-40280 in Linux
Summary
by MITRE • 12/07/2025
In the Linux kernel, the following vulnerability has been resolved:
tipc: Fix use-after-free in tipc_mon_reinit_self().
syzbot reported use-after-free of tipc_net(net)->monitors[]
in tipc_mon_reinit_self(). [0]
The array is protected by RTNL, but tipc_mon_reinit_self() iterates over it without RTNL.
tipc_mon_reinit_self() is called from tipc_net_finalize(), which is always under RTNL except for tipc_net_finalize_work().
Let's hold RTNL in tipc_net_finalize_work().
[0]:
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 Read of size 1 at addr ffff88805eae1030 by task kworker/0:7/5989
CPU: 0 UID: 0 PID: 5989 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Workqueue: events tipc_net_finalize_work Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:568 kasan_check_byte include/linux/kasan.h:399 [inline]
lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162 rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline]
rwbase_rtmutex_lock_state kernel/locking/spinlock_rt.c:160 [inline]
rwbase_write_lock+0xd3/0x7e0 kernel/locking/rwbase_rt.c:244 rt_write_lock+0x76/0x110 kernel/locking/spinlock_rt.c:243 write_lock_bh include/linux/rwlock_rt.h:99 [inline]
tipc_mon_reinit_self+0x79/0x430 net/tipc/monitor.c:718 tipc_net_finalize+0x115/0x190 net/tipc/net.c:140 process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
Allocated by task 6089: kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405 kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x1a8/0x320 mm/slub.c:4407 kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
tipc_mon_create+0xc3/0x4d0 net/tipc/monitor.c:657 tipc_enable_bearer net/tipc/bearer.c:357 [inline]
__tipc_nl_bearer_enable+0xe16/0x13f0 net/tipc/bearer.c:1047 __tipc_nl_compat_doit net/tipc/netlink_compat.c:371 [inline]
tipc_nl_compat_doit+0x3bc/0x5f0 net/tipc/netlink_compat.c:393 tipc_nl_compat_handle net/tipc/netlink_compat.c:-1 [inline]
tipc_nl_compat_recv+0x83c/0xbe0 net/tipc/netlink_compat.c:1321 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x846/0xa10 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:729 ____sys_sendmsg+0x508/0x820 net/socket.c:2614 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668 __sys_sendmsg net/socket.c:2700 [inline]
__do_sys_sendmsg net/socket.c:2705 [inline]
__se_sys_sendmsg net/socket.c:2703 [inline]
__x64_sys_sendmsg+0x1a1/0x260 net/socket.c:2703 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/ ---truncated---
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Analysis
by VulDB Data Team • 02/23/2026
The vulnerability described in CVE-2025-40280 is a use-after-free issue within the Linux kernel's TIPC (Transparent Inter-Process Communication) subsystem. This flaw occurs in the function tipc_mon_reinit_self(), which is responsible for reinitializing monitor structures in the TIPC network stack. The issue stems from improper locking mechanisms during access to the tipc_net(net)->monitors[] array. While the array is protected by the RTNL (Read-Two-Write Lock) mechanism, the function tipc_mon_reinit_self() iterates over this array without acquiring the necessary RTNL lock, leading to a potential race condition. The kernel's memory safety checker KASAN detected this issue when attempting to access freed memory, indicating a slab-use-after-free error during a spinlock operation. This vulnerability is particularly concerning as it can be triggered through kernel workqueue execution in tipc_net_finalize_work(), which is invoked from various network configuration paths. The flaw can be exploited to cause system instability or potentially enable privilege escalation depending on the execution context. The root cause lies in the inconsistent locking strategy where the function tipc_net_finalize_work() fails to hold the RTNL lock during the iteration of the monitors array, violating the kernel's locking protocol. The issue is classified under CWE-415 as a double free or use-after-free vulnerability and aligns with ATT&CK technique T1068 which involves exploiting local privileges to gain system-level access. The vulnerability demonstrates a classic concurrency issue in kernel space where proper synchronization primitives are not consistently applied across all code paths accessing shared data structures. The specific trigger involves the kernel worker thread kworker/0:7 executing tipc_net_finalize_work(), which eventually calls tipc_mon_reinit_self() without proper locking, leading to memory corruption. This flaw underscores the critical importance of maintaining consistent locking across all access paths to shared kernel data structures and highlights the necessity of thorough code review for concurrent access patterns in kernel subsystems. Mitigation requires ensuring that RTNL is held during all operations accessing the monitors array within tipc_mon_reinit_self() to prevent race conditions and maintain memory integrity during concurrent access scenarios. The fix involves modifying tipc_net_finalize_work() to acquire the RTNL lock before invoking tipc_mon_reinit_self(), thereby ensuring consistent protection of the shared array elements. This vulnerability exemplifies how seemingly minor locking inconsistencies can lead to serious security implications in kernel space operations, particularly in network subsystems where concurrent access is common.