CVE-2025-71142

In the Linux kernel, the following vulnerability has been resolved:

cpuset: fix warning when disabling remote partition

A warning was triggered as follows:

WARNING: kernel/cgroup/cpuset.c:1651 at remote_partition_disable+0xf7/0x110

RIP: 0010:remote_partition_disable+0xf7/0x110

RSP: 0018:ffffc90001947d88 EFLAGS: 00000206

RAX: 0000000000007fff RBX: ffff888103b6e000 RCX: 0000000000006f40

RDX: 0000000000006f00 RSI: ffffc90001947da8 RDI: ffff888103b6e000

RBP: ffff888103b6e000 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000001 R11: ffff88810b2e2728 R12: ffffc90001947da8

R13: 0000000000000000 R14: ffffc90001947da8 R15: ffff8881081f1c00

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f55c8bbe0b2 CR3: 000000010b14c000 CR4: 00000000000006f0

Call Trace:

<TASK>

update_prstate+0x2d3/0x580

cpuset_partition_write+0x94/0xf0

kernfs_fop_write_iter+0x147/0x200

vfs_write+0x35d/0x500

ksys_write+0x66/0xe0

do_syscall_64+0x6b/0x390

entry_SYSCALL_64_after_hwframe+0x4b/0x53

RIP: 0033:0x7f55c8cd4887

Reproduction steps (on a 16-CPU machine):

# cd /sys/fs/cgroup/

# mkdir A1

# echo +cpuset > A1/cgroup.subtree_control

# echo "0-14" > A1/cpuset.cpus.exclusive

# mkdir A1/A2

# echo "0-14" > A1/A2/cpuset.cpus.exclusive

# echo "root" > A1/A2/cpuset.cpus.partition

# echo 0 > /sys/devices/system/cpu/cpu15/online

# echo member > A1/A2/cpuset.cpus.partition

When CPU 15 is offlined, subpartitions_cpus gets cleared because no CPUs

remain available for the top_cpuset, forcing partitions to share CPUs with

the top_cpuset. In this scenario, disabling the remote partition triggers

a warning stating that effective_xcpus is not a subset of

subpartitions_cpus. Partitions should be invalidated in this case to

inform users that the partition is now invalid(cpus are shared with

top_cpuset).

To fix this issue:

1. Only emit the warning only if subpartitions_cpus is not empty and the

effective_xcpus is not a subset of subpartitions_cpus.

2. During the CPU hotplug process, invalidate partitions if

subpartitions_cpus is empty.