CVE-2025-21727

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Source
https://cve.org/CVERecord?id=CVE-2025-21727
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21727.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2025-21727
Downstream
Related
Published
2025-02-27T02:07:33Z
Modified
2026-08-12T03:30:16Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
padata: fix UAF in padata_reorder
Details

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: 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_find_next(pd, true); // using pd queue_work_on ... padata_serial_worker crypto_del_alg padata_put_pd_cnt // sub refcnt padata_free_shell padata_put_pd(ps->pd); // pd is freed // loop again, but pd is freed // call padata_find_next, UAF }

In the padata_reorder function, when it loops in 'while', if the alg is deleted, the refcnt may be decreased to 0 before entering 'padata_find_next', which leads to UAF.

As mentioned in [1], do_serial is supposed to be called with BHs disabled and always happen under RCU protection, to address this issue, add synchronize_rcu() in 'padata_free_shell' wait for all _do_serial calls to finish.

[1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/ [2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21727.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
b128a30409356df65f1a51cff3eb986cac8cfedc
Fixed
f78170bee51469734b1a306a74fc5f777bb22ba6
Fixed
f3e0b9f790f8e8065d59e67b565a83154d9f3079
Fixed
0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd
Fixed
bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de
Fixed
573ac9c70bf7885dc85d82fa44550581bfc3b738
Fixed
80231f069240d52e98b6a317456c67b2eafd0781
Fixed
e01780ea4661172734118d2a5f41bc9720765668

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21727.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
5.4.0
Fixed
5.10.235
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.179
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.129
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.76
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.13
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.13.2

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21727.json"