CVE-2024-56701

/// Technical 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/

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References