CVE-2024-56701 powerpc/pseries: Fix dtl_access_lock to be a rw_semaphore
A local attacker can trigger a kernel bug by writing to a proc file, causing a sleeping function call in atomic context and leading to a system crash.
- 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-2024-56701?
CVE-2024-56701 is a medium-severity denial of service vulnerability in Linux kernel, published on 28 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:
powerpc/pseries: Fix dtl_access_lock to be a rw_semaphore
The dtl_access_lock needs to be a rw_sempahore, a sleeping lock, because the code calls kmalloc() while holding it, which can sleep:
# echo 1 > /proc/powerpc/vcpudispatch_stats BUG: sleeping function called from invalid context at include/linux/sched/mm.h:337 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 199, name: sh preempt_count: 1, expected: 0 3 locks held by sh/199: #0: c00000000a0743f8 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x324/0x438 #1: c0000000028c7058 (dtl_enable_mutex){+.+.}-{3:3}, at: vcpudispatch_stats_write+0xd4/0x5f4 #2: c0000000028c70b8 (dtl_access_lock){+.+.}-{2:2}, at: vcpudispatch_stats_write+0x220/0x5f4 CPU: 0 PID: 199 Comm: sh Not tainted 6.10.0-rc4 #152 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries Call Trace: dump_stack_lvl+0x130/0x148 (unreliable) __might_resched+0x174/0x410 kmem_cache_alloc_noprof+0x340/0x3d0 alloc_dtl_buffers+0x124/0x1ac vcpudispatch_stats_write+0x2a8/0x5f4 proc_reg_write+0xf4/0x150 vfs_write+0xfc/0x438 ksys_write+0x88/0x148 system_call_exception+0x1c4/0x5a0 system_call_common+0xf4/0x258
Which versions are affected by CVE-2024-56701?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-56701?
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-2024-56701 being exploited?
There is no known exploitation of CVE-2024-56701 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-56701, DEBIAN-CVE-2024-56701, GHSA-qf2f-rv74-7c9g, ROOT-OS-DEBIAN-11-CVE-2024-56701, UBUNTU-CVE-2024-56701.