CVE-2024-56610 kcsan: Turn report_filterlist_lock into a raw_spinlock
A locking bug in the Linux kernel's KCSAN module can cause a system crash when data races are reported in interrupt contexts on PREEMPT_RT kernels.
- 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-2024-56610?
CVE-2024-56610 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Dec 2024. 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:
kcsan: Turn report_filterlist_lock into a raw_spinlock
Ran Xiaokai reports that with a KCSAN-enabled PREEMPT_RT kernel, we can see splats like:
| BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 | preempt_count: 10002, expected: 0 | RCU nest depth: 0, expected: 0 | no locks held by swapper/1/0. | irq event stamp: 156674 | hardirqs last enabled at (156673): [<ffffffff81130bd9>] do_idle+0x1f9/0x240 | hardirqs last disabled at (156674): [<ffffffff82254f84>] sysvec_apic_timer_interrupt+0x14/0xc0 | softirqs last enabled at (0): [<ffffffff81099f47>] copy_process+0xfc7/0x4b60 | softirqs last disabled at (0): [<0000000000000000>] 0x0 | Preemption disabled at: | [<ffffffff814a3e2a>] paint_ptr+0x2a/0x90 | CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.11.0+ #3 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 | Call Trace: | <IRQ> | dump_stack_lvl+0x7e/0xc0 | dump_stack+0x1d/0x30 | __might_resched+0x1a2/0x270 | rt_spin_lock+0x68/0x170 | kcsan_skip_report_debugfs+0x43/0xe0 | print_report+0xb5/0x590 | kcsan_report_known_origin+0x1b1/0x1d0 | kcsan_setup_watchpoint+0x348/0x650 | __tsan_unaligned_write1+0x16d/0x1d0 | hrtimer_interrupt+0x3d6/0x430 | __sysvec_apic_timer_interrupt+0xe8/0x3a0 | sysvec_apic_timer_interrupt+0x97/0xc0 | </IRQ>
On a detected data race, KCSAN's reporting logic checks if it should filter the report. That list is protected by the report_filterlist_lock *non-raw* spinlock which may sleep on RT kernels.
Since KCSAN may report data races in any context, convert it to a raw_spinlock.
This requires being careful about when to allocate memory for the filter list itself which can be done via KCSAN's debugfs interface. Concurrent modification of the filter list via debugfs should be rare: the chosen strategy is to optimistically pre-allocate memory before the critical section and discard if unused.
Which versions are affected by CVE-2024-56610?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-56610?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-56610 being exploited?
There is no known exploitation of CVE-2024-56610 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-56610, DEBIAN-CVE-2024-56610, GHSA-355g-892p-7fp8, UBUNTU-CVE-2024-56610.