CVE-2023-53832

/// Technical description

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

md/raid10: fix null-ptr-deref in raid10_sync_request

init_resync() inits mempool and sets conf->have_replacemnt at the beginning

of sync, close_sync() frees the mempool when sync is completed.

After [1] recovery might be skipped and init_resync() is called but

close_sync() is not. null-ptr-deref occurs with r10bio->dev[i].repl_bio.

The following is one way to reproduce the issue.

1) create a array, wait for resync to complete, mddev->recovery_cp is set

to MaxSector.

2) recovery is woken and it is skipped. conf->have_replacement is set to

0 in init_resync(). close_sync() not called.

3) some io errors and rdev A is set to WantReplacement.

4) a new device is added and set to A's replacement.

5) recovery is woken, A have replacement, but conf->have_replacemnt is

0. r10bio->dev[i].repl_bio will not be alloced and null-ptr-deref

occurs.

Fix it by not calling init_resync() if recovery skipp

/// 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