GHSA-WVMF-XH97-GMFR
Vulnerability from github – Published: 2025-02-27 03:34 – Updated: 2026-05-12 15:30In 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/
{
"affected": [],
"aliases": [
"CVE-2025-21727"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-27T02:15:16Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\npadata: fix UAF in padata_reorder\n\nA bug was found when run ltp test:\n\nBUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0\nRead of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206\n\nCPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+\nWorkqueue: pdecrypt_parallel padata_parallel_worker\nCall Trace:\n\u003cTASK\u003e\ndump_stack_lvl+0x32/0x50\nprint_address_description.constprop.0+0x6b/0x3d0\nprint_report+0xdd/0x2c0\nkasan_report+0xa5/0xd0\npadata_find_next+0x29/0x1a0\npadata_reorder+0x131/0x220\npadata_parallel_worker+0x3d/0xc0\nprocess_one_work+0x2ec/0x5a0\n\nIf \u0027mdelay(10)\u0027 is added before calling \u0027padata_find_next\u0027 in the\n\u0027padata_reorder\u0027 function, this issue could be reproduced easily with\nltp test (pcrypt_aead01).\n\nThis can be explained as bellow:\n\npcrypt_aead_encrypt\n...\npadata_do_parallel\nrefcount_inc(\u0026pd-\u003erefcnt); // add refcnt\n...\npadata_do_serial\npadata_reorder // pd\nwhile (1) {\npadata_find_next(pd, true); // using pd\nqueue_work_on\n...\npadata_serial_worker\t\t\t\tcrypto_del_alg\npadata_put_pd_cnt // sub refcnt\n\t\t\t\t\t\tpadata_free_shell\n\t\t\t\t\t\tpadata_put_pd(ps-\u003epd);\n\t\t\t\t\t\t// pd is freed\n// loop again, but pd is freed\n// call padata_find_next, UAF\n}\n\nIn the padata_reorder function, when it loops in \u0027while\u0027, if the alg is\ndeleted, the refcnt may be decreased to 0 before entering\n\u0027padata_find_next\u0027, which leads to UAF.\n\nAs mentioned in [1], do_serial is supposed to be called with BHs disabled\nand always happen under RCU protection, to address this issue, add\nsynchronize_rcu() in \u0027padata_free_shell\u0027 wait for all _do_serial calls\nto finish.\n\n[1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/\n[2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/",
"id": "GHSA-wvmf-xh97-gmfr",
"modified": "2026-05-12T15:30:46Z",
"published": "2025-02-27T03:34:02Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21727"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/573ac9c70bf7885dc85d82fa44550581bfc3b738"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/80231f069240d52e98b6a317456c67b2eafd0781"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e01780ea4661172734118d2a5f41bc9720765668"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f3e0b9f790f8e8065d59e67b565a83154d9f3079"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f78170bee51469734b1a306a74fc5f777bb22ba6"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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