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Fencer Vulns
medium 5.5

CVE-2024-36966 json

erofs: reliably distinguish block based and fscache mode

published 2024-06-08 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-36316

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

erofs: reliably distinguish block based and fscache mode

When erofs_kill_sb() is called in block dev based mode, s_bdev may not have been initialised yet, and if CONFIG_EROFS_FS_ONDEMAND is enabled, it will be mistaken for fscache mode, and then attempt to free an anon_dev that has never been allocated, triggering the following warning:

============================================ ida_free called for id=0 which is not allocated. WARNING: CPU: 14 PID: 926 at lib/idr.c:525 ida_free+0x134/0x140 Modules linked in: CPU: 14 PID: 926 Comm: mount Not tainted 6.9.0-rc3-dirty #630 RIP: 0010:ida_free+0x134/0x140 Call Trace: <TASK> erofs_kill_sb+0x81/0x90 deactivate_locked_super+0x35/0x80 get_tree_bdev+0x136/0x1e0 vfs_get_tree+0x2c/0xf0 do_new_mount+0x190/0x2f0 [...] ============================================

Now when erofs_kill_sb() is called, erofs_sb_info must have been initialised, so use sbi->fsid to distinguish between the two modes.

Patch / fix

  • Linux Linux 6.6.32, 6.8.11, 6.9
  • linux Debian 14, Debian 13 6.8.11-1

debian advisories DEBIAN-CVE-2024-36966

  • linux Ubuntu 24.04 LTS 6.8.0-40.40
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1013.14
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1012.13
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1008.11
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1010.10
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1012.14
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1009.10
  • linux-riscv Ubuntu 24.04 LTS 6.8.0-40.40.1

ubuntu advisories UBUNTU-CVE-2024-36966

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-36966 updated cvss 5.5

kernel: erofs: reliably distinguish block based and fscache mode

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-824 Access of Uninitialized Pointer
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.