CVE-2022-49006

/// Technical description

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

tracing: Free buffers when a used dynamic event is removed

After 65536 dynamic events have been added and removed, the "type" field

of the event then uses the first type number that is available (not

currently used by other events). A type number is the identifier of the

binary blobs in the tracing ring buffer (known as events) to map them to

logic that can parse the binary blob.

The issue is that if a dynamic event (like a kprobe event) is traced and

is in the ring buffer, and then that event is removed (because it is

dynamic, which means it can be created and destroyed), if another dynamic

event is created that has the same number that new event's logic on

parsing the binary blob will be used.

To show how this can be an issue, the following can crash the kernel:

# cd /sys/kernel/tracing

# for i in `seq 65536`; do

echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events

# done

For every iteration of

/// 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