CVE-2024-56701: powerpc/pseries: Fix dtl_access_lock to be a rw_semaphore

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-12-28 · updated 2026-06-17

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

Affected products

Linux kernel: from 5.3 before 5.10.231; from 5.11 before 5.15.174; from 5.16 before 6.1.120; from 6.2 before 6.6.64; from 6.7 before 6.11.11; from 6.12 before 6.12.2 — fixed in 5.10.231, 5.15.174, 6.1.120, 6.11.11, 6.12.2, 6.6.64

How to fix

Upgrade to a fixed version: Linux kernel 5.10.231, 5.15.174, 6.1.120, 6.11.11. Check the vendor advisory for mitigations.

References

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