{"cve":"CVE-2025-21727","nvd":{"published":"2025-02-27T02:15:16.423","modified":"2026-10-15T02:17:30.770","status":"Modified","description":"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<TASK>\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 'mdelay(10)' is added before calling 'padata_find_next' in the\n'padata_reorder' 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(&pd->refcnt); // 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->pd);\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 'while', if the alg is\ndeleted, the refcnt may be decreased to 0 before entering\n'padata_find_next', 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 'padata_free_shell' 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/","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd","https://git.kernel.org/stable/c/573ac9c70bf7885dc85d82fa44550581bfc3b738","https://git.kernel.org/stable/c/80231f069240d52e98b6a317456c67b2eafd0781","https://git.kernel.org/stable/c/bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de","https://git.kernel.org/stable/c/e01780ea4661172734118d2a5f41bc9720765668"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2025-21727","score":0.00222,"percentile":0.12724,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}