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Review reviewHigh

CVE-2021-47303

Linux Linux, linux kernel

In the Linux kernel, the following vulnerability has been resolved: bpf: Track subprog poke descriptors correctly and fix use-after-free Subprograms are calling map_poke_track(), but on program release there is no hook to call map_poke_untrack(). However, on program release, the aux memory (and poke descriptor table) is freed even though we still have a reference to it in the element list of the map aux data. When we run map_poke_run(), we then end up accessing free'd memory, triggering KASAN in prog_array_map_poke_run(): [...] [ 402.824689] BUG: KASAN: use-after-free in prog_array_map_poke...

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2024.05.22
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: bpf: Track subprog poke descriptors correctly and fix use-after-free Subprograms are calling map_poke_track(), but on program release there is no hook to call map_poke_untrack(). However, on program release, the aux memory (and poke descriptor table) is freed even though we still have a reference to it in the element list of the map aux data. When we run map_poke_run(), we then end up accessing free'd memory, triggering KASAN in prog_array_map_poke_run(): [...] [ 402.824689] BUG: KASAN: use-after-free in prog_array_map_poke...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= a748c6975dea325da540610c2ba9b5f332c603e6 < a9f36bf3613c65cb587c70fac655c775d911409b, >= a748c6975dea325da540610c2ba9b5f332c603e6 < 599148d40366bd5d1d504a3a8fcd65e21107e500, >= a748c6975dea325da540610c2ba9b5f332c603e6 < f263a81451c12da5a342d90572e317e611846f2c, >= 5.10, >= 5.10 < 5.10.53, >= 5.11 < 5.13.5, 5.14
Fixed versions
5.10.53, 5.13.5

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-416