CVE-2025-21727

/// Technical description

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

padata: fix UAF in padata_reorder

A bug was found when run ltp test:

BUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0

Read of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206

CPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+

Workqueue: pdecrypt_parallel padata_parallel_worker

Call Trace:

<TASK>

dump_stack_lvl+0x32/0x50

print_address_description.constprop.0+0x6b/0x3d0

print_report+0xdd/0x2c0

kasan_report+0xa5/0xd0

padata_find_next+0x29/0x1a0

padata_reorder+0x131/0x220

padata_parallel_worker+0x3d/0xc0

process_one_work+0x2ec/0x5a0

If 'mdelay(10)' is added before calling 'padata_find_next' in the

'padata_reorder' function, this issue could be reproduced easily with

ltp test (pcrypt_aead01).

This can be explained as bellow:

pcrypt_aead_encrypt

...

padata_do_parallel

refcount_inc(&pd->refcnt); // add refcnt

...

padata_do_serial

padata_reorder // pd

while (1) {

padata

/// 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