CVE-2021-46974 (GCVE-0-2021-46974)

Vulnerability from cvelistv5 – Published: 2024-02-27 18:47 – Updated: 2026-08-05 08:45
VLAI
Title
bpf: Fix masking negation logic upon negative dst register
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix masking negation logic upon negative dst register The negation logic for the case where the off_reg is sitting in the dst register is not correct given then we cannot just invert the add to a sub or vice versa. As a fix, perform the final bitwise and-op unconditionally into AX from the off_reg, then move the pointer from the src to dst and finally use AX as the source for the original pointer arithmetic operation such that the inversion yields a correct result. The single non-AX mov in between is possible given constant blinding is retaining it as it's not an immediate based operation.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-03-05 16:32 UTC
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: ae03b6b1c880a03d4771257336dc3bca156dd51b , < 4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba (git)
Affected: f92a819b4cbef8c9527d9797110544b2055a4b96 , < 0e2dfdc74a7f4036127356d42ea59388f153f42c (git)
Affected: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 , < 53e0db429b37a32b8fc706d0d90eb4583ad13848 (git)
Affected: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 , < 2cfa537674cd1051a3b8111536d77d0558f33d5d (git)
Affected: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 , < 6eba92a4d4be8feb4dc33976abac544fa99d6ecc (git)
Affected: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 , < 7cf64d8679ca1cb20cf57d6a88bfee79a0922a66 (git)
Affected: 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 , < b9b34ddbe2076ade359cd5ce7537d5ed019e9807 (git)
Affected: 078da99d449f64ca04d459cdbdcce513b64173cd (git)
Affected: 4.14.113 , < 4.14.233 (semver)
Affected: 4.19.19 , < 4.19.190 (semver)
Affected: 4.20.6 , < 4.21 (semver)
Create a notification for this product.
Linux Linux Affected: 5.0
Unaffected: 0 , < 5.0 (semver)
Unaffected: 4.14.233 , ≤ 4.14.* (semver)
Unaffected: 4.19.190 , ≤ 4.19.* (semver)
Unaffected: 5.4.117 , ≤ 5.4.* (semver)
Unaffected: 5.10.35 , ≤ 5.10.* (semver)
Unaffected: 5.11.19 , ≤ 5.11.* (semver)
Unaffected: 5.12.2 , ≤ 5.12.* (semver)
Unaffected: 5.13 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
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      "product_status:known_affected": "42",
      "product_status:known_not_affected": "156",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Fix masking negation logic upon negative dst register",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-46974.json",
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      "product_status:recommended": "222",
      "source": "SUSE CSAF VEX",
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      "title": "SUSE CVE CVE-2021-46974",
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Spectre-style BPF masking bugs do not provide integrity impact.\\nA:H - The incorrect add/sub inversion for negative dst produces architecturally wrong pointers (e.g. offset - pointer), so subsequent verifier-approved loads/stores oops/panic the kernel.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"ae03b6b1c880a03d4771257336dc3bca156dd51b\", \"lessThan\": \"4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"f92a819b4cbef8c9527d9797110544b2055a4b96\", \"lessThan\": \"0e2dfdc74a7f4036127356d42ea59388f153f42c\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"979d63d50c0c0f7bc537bf821e056cc9fe5abd38\", \"lessThan\": \"53e0db429b37a32b8fc706d0d90eb4583ad13848\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"979d63d50c0c0f7bc537bf821e056cc9fe5abd38\", \"lessThan\": \"2cfa537674cd1051a3b8111536d77d0558f33d5d\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"979d63d50c0c0f7bc537bf821e056cc9fe5abd38\", \"lessThan\": \"6eba92a4d4be8feb4dc33976abac544fa99d6ecc\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"979d63d50c0c0f7bc537bf821e056cc9fe5abd38\", \"lessThan\": \"7cf64d8679ca1cb20cf57d6a88bfee79a0922a66\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"979d63d50c0c0f7bc537bf821e056cc9fe5abd38\", \"lessThan\": \"b9b34ddbe2076ade359cd5ce7537d5ed019e9807\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"078da99d449f64ca04d459cdbdcce513b64173cd\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"4.14.113\", \"lessThan\": \"4.14.233\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"4.19.19\", \"lessThan\": \"4.19.190\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"4.20.6\", \"lessThan\": \"4.21\", \"versionType\": \"semver\"}], \"programFiles\": [\"kernel/bpf/verifier.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5.0\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"5.0\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"4.14.233\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"4.14.*\"}, {\"status\": \"unaffected\", \"version\": \"4.19.190\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"4.19.*\"}, {\"status\": \"unaffected\", \"version\": \"5.4.117\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.4.*\"}, {\"status\": \"unaffected\", \"version\": \"5.10.35\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.11.19\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.11.*\"}, {\"status\": \"unaffected\", \"version\": \"5.12.2\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.12.*\"}, {\"status\": \"unaffected\", \"version\": \"5.13\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"kernel/bpf/verifier.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba\"}, {\"url\": \"https://git.kernel.org/stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c\"}, {\"url\": \"https://git.kernel.org/stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848\"}, {\"url\": \"https://git.kernel.org/stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d\"}, {\"url\": \"https://git.kernel.org/stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc\"}, {\"url\": \"https://git.kernel.org/stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66\"}, {\"url\": \"https://git.kernel.org/stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbpf: Fix masking negation logic upon negative dst register\\n\\nThe negation logic for the case where the off_reg is sitting in the\\ndst register is not correct given then we cannot just invert the add\\nto a sub or vice versa. As a fix, perform the final bitwise and-op\\nunconditionally into AX from the off_reg, then move the pointer from\\nthe src to dst and finally use AX as the source for the original\\npointer arithmetic operation such that the inversion yields a correct\\nresult. The single non-AX mov in between is possible given constant\\nblinding is retaining it as it\u0027s not an immediate based operation.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"4.14.233\", \"versionStartIncluding\": \"4.14.113\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"4.19.190\", \"versionStartIncluding\": \"4.19.19\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.4.117\", \"versionStartIncluding\": \"5.0\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.35\", \"versionStartIncluding\": \"5.0\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.11.19\", \"versionStartIncluding\": \"5.0\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.12.2\", \"versionStartIncluding\": \"5.0\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.13\", \"versionStartIncluding\": \"5.0\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"4.20.6\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T08:45:20.335Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-46974\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T08:45:20.335Z\", \"dateReserved\": \"2024-02-27T18:42:55.944Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-02-27T18:47:08.487Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.