{"cve":"CVE-2025-38050","nvd":{"published":"2025-06-18T10:15:37.570","modified":"2026-06-17T09:15:57.213","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix kernel NULL pointer dereference when replacing free hugetlb folios\n\nA kernel crash was observed when replacing free hugetlb folios:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000028\nPGD 0 P4D 0\nOops: Oops: 0000 [#1] SMP NOPTI\nCPU: 28 UID: 0 PID: 29639 Comm: test_cma.sh Tainted 6.15.0-rc6-zp #41 PREEMPT(voluntary)\nRIP: 0010:alloc_and_dissolve_hugetlb_folio+0x1d/0x1f0\nRSP: 0018:ffffc9000b30fa90 EFLAGS: 00010286\nRAX: 0000000000000000 RBX: 0000000000342cca RCX: ffffea0043000000\nRDX: ffffc9000b30fb08 RSI: ffffea0043000000 RDI: 0000000000000000\nRBP: ffffc9000b30fb20 R08: 0000000000001000 R09: 0000000000000000\nR10: ffff88886f92eb00 R11: 0000000000000000 R12: ffffea0043000000\nR13: 0000000000000000 R14: 00000000010c0200 R15: 0000000000000004\nFS:  00007fcda5f14740(0000) GS:ffff8888ec1d8000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000000000000028 CR3: 0000000391402000 CR4: 0000000000350ef0\nCall Trace:\n<TASK>\n replace_free_hugepage_folios+0xb6/0x100\n alloc_contig_range_noprof+0x18a/0x590\n ? srso_return_thunk+0x5/0x5f\n ? down_read+0x12/0xa0\n ? srso_return_thunk+0x5/0x5f\n cma_range_alloc.constprop.0+0x131/0x290\n __cma_alloc+0xcf/0x2c0\n cma_alloc_write+0x43/0xb0\n simple_attr_write_xsigned.constprop.0.isra.0+0xb2/0x110\n debugfs_attr_write+0x46/0x70\n full_proxy_write+0x62/0xa0\n vfs_write+0xf8/0x420\n ? srso_return_thunk+0x5/0x5f\n ? filp_flush+0x86/0xa0\n ? srso_return_thunk+0x5/0x5f\n ? filp_close+0x1f/0x30\n ? srso_return_thunk+0x5/0x5f\n ? do_dup2+0xaf/0x160\n ? srso_return_thunk+0x5/0x5f\n ksys_write+0x65/0xe0\n do_syscall_64+0x64/0x170\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThere is a potential race between __update_and_free_hugetlb_folio() and\nreplace_free_hugepage_folios():\n\nCPU1                              CPU2\n__update_and_free_hugetlb_folio   replace_free_hugepage_folios\n                                    folio_test_hugetlb(folio)\n                                    -- It's still hugetlb folio.\n\n  __folio_clear_hugetlb(folio)\n  hugetlb_free_folio(folio)\n                                    h = folio_hstate(folio)\n                                    -- Here, h is NULL pointer\n\nWhen the above race condition occurs, folio_hstate(folio) returns NULL,\nand subsequent access to this NULL pointer will cause the system to crash.\nTo resolve this issue, execute folio_hstate(folio) under the protection\nof the hugetlb_lock lock, ensuring that folio_hstate(folio) does not\nreturn NULL.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/113ed54ad276c352ee5ce109bdcf0df118a43bda","https://git.kernel.org/stable/c/e97283978a9848190d451f7038ac399613445f79"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:03:23.287444849+00:00"},"epss":{"cve":"CVE-2025-38050","score":0.00163,"percentile":0.05533,"date":"2026-10-31"},"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."]}