CVE-2025-37993 can: m_can: m_can_class_allocate_dev(): initialize spin lock on device probe
An uninitialized spin lock in the Linux kernel m_can driver causes a kernel bug and potential denial of service when sending CAN frames.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-37993?
CVE-2025-37993 is a medium-severity vulnerability in Linux kernel, published on 29 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
can: m_can: m_can_class_allocate_dev(): initialize spin lock on device probe
The spin lock tx_handling_spinlock in struct m_can_classdev is not being initialized. This leads the following spinlock bad magic complaint from the kernel, eg. when trying to send CAN frames with cansend from can-utils:
| BUG: spinlock bad magic on CPU#0, cansend/95 | lock: 0xff60000002ec1010, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0 | CPU: 0 UID: 0 PID: 95 Comm: cansend Not tainted 6.15.0-rc3-00032-ga79be02bba5c #5 NONE | Hardware name: MachineWare SIM-V (DT) | Call Trace: | [<ffffffff800133e0>] dump_backtrace+0x1c/0x24 | [<ffffffff800022f2>] show_stack+0x28/0x34 | [<ffffffff8000de3e>] dump_stack_lvl+0x4a/0x68 | [<ffffffff8000de70>] dump_stack+0x14/0x1c | [<ffffffff80003134>] spin_dump+0x62/0x6e | [<ffffffff800883ba>] do_raw_spin_lock+0xd0/0x142 | [<ffffffff807a6fcc>] _raw_spin_lock_irqsave+0x20/0x2c | [<ffffffff80536dba>] m_can_start_xmit+0x90/0x34a | [<ffffffff806148b0>] dev_hard_start_xmit+0xa6/0xee | [<ffffffff8065b730>] sch_direct_xmit+0x114/0x292 | [<ffffffff80614e2a>] __dev_queue_xmit+0x3b0/0xaa8 | [<ffffffff8073b8fa>] can_send+0xc6/0x242 | [<ffffffff8073d1c0>] raw_sendmsg+0x1a8/0x36c | [<ffffffff805ebf06>] sock_write_iter+0x9a/0xee | [<ffffffff801d06ea>] vfs_write+0x184/0x3a6 | [<ffffffff801d0a88>] ksys_write+0xa0/0xc0 | [<ffffffff801d0abc>] __riscv_sys_write+0x14/0x1c | [<ffffffff8079ebf8>] do_trap_ecall_u+0x168/0x212 | [<ffffffff807a830a>] handle_exception+0x146/0x152
Initializing the spin lock in m_can_class_allocate_dev solves that problem.
Which versions are affected by CVE-2025-37993?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-37993?
Apply the vendor's patch.
Is CVE-2025-37993 being exploited?
There is no known exploitation of CVE-2025-37993 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-37993, DEBIAN-CVE-2025-37993, GHSA-cc89-xr3w-vpvf, UBUNTU-CVE-2025-37993.