Vulnerability in Linux

CVE-2021-47214

In the Linux kernel, the following vulnerability has been resolved: hugetlb, userfaultfd: fix reservation restore on userfaultfd error Currently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we bail out using "goto out_release_unlock;" in the cases where idx >= size, or !huge_pte_none(), the code will detect that new_pagecache_page == false, and so call restore_reserve_on_error(). In this case I see restore_reserve_on_error() delete the reservation, and the following call to remove_inode_hugepages() will increment h->resv_hugepages causing a 100% reproducible leak. We should treat the is_continue case similar to adding a page into the pagecache and set new_pagecache_page to true, to indicate that there is no reservation to restore on the error path, and we need not call restore_reserve_on_error(). Rename new_pagecache_page to page_in_pagecache to make that clear.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (8.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 8.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-47214: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Linux — versions 5.14, 515b6124df6a84c957c5cc6bb6e8309dae7b1e9c, c7b1850dfb41d0b4154aca8dbc04777fbd75616f
  • Linux Kernel — versions 5.13.13, 5.16

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-47214?
CVE-2021-47214 is a medium-severity vulnerability in Linux, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 5.5/10. Published 2024-04-10.
How severe is CVE-2021-47214?
Medium severity. CVSS v3 base score is 5.5 out of 10.