CVE-2023-54173

Technical Description

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

bpf: Disable preemption in bpf_event_output

We received report [1] of kernel crash, which is caused by

using nesting protection without disabled preemption.

The bpf_event_output can be called by programs executed by

bpf_prog_run_array_cg function that disabled migration but

keeps preemption enabled.

This can cause task to be preempted by another one inside the

nesting protection and lead eventually to two tasks using same

perf_sample_data buffer and cause crashes like:

BUG: kernel NULL pointer dereference, address: 0000000000000001

#PF: supervisor instruction fetch in kernel mode

#PF: error_code(0x0010) - not-present page

...

? perf_output_sample+0x12a/0x9a0

? finish_task_switch.isra.0+0x81/0x280

? perf_event_output+0x66/0xa0

? bpf_event_output+0x13a/0x190

? bpf_event_output_data+0x22/0x40

? bpf_prog_dfc84bbde731b257_cil_sock4_connect+0x40a/0xacb

? xa_load+0x87/0xe0

? __cgroup_bpf_run_filte

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