CVE-2022-49085

/// Technical description

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

drbd: Fix five use after free bugs in get_initial_state

In get_initial_state, it calls notify_initial_state_done(skb,..) if

cb->args[5]==1. If genlmsg_put() failed in notify_initial_state_done(),

the skb will be freed by nlmsg_free(skb).

Then get_initial_state will goto out and the freed skb will be used by

return value skb->len, which is a uaf bug.

What's worse, the same problem goes even further: skb can also be

freed in the notify_*_state_change -> notify_*_state calls below.

Thus 4 additional uaf bugs happened.

My patch lets the problem callee functions: notify_initial_state_done

and notify_*_state_change return an error code if errors happen.

So that the error codes could be propagated and the uaf bugs can be avoid.

v2 reports a compilation warning. This v3 fixed this warning and built

successfully in my local environment with no additional warnings.

v2: https://lore.kernel.org/patchwork/patch/1435218/

/// 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