CVE-2021-46969 (GCVE-0-2021-46969)

Vulnerability from cvelistv5 – Published: 2024-02-27 18:47 – Updated: 2026-08-05 08:45
VLAI
Title
bus: mhi: core: Fix invalid error returning in mhi_queue
Summary
In the Linux kernel, the following vulnerability has been resolved: bus: mhi: core: Fix invalid error returning in mhi_queue mhi_queue returns an error when the doorbell is not accessible in the current state. This can happen when the device is in non M0 state, like M3, and needs to be waken-up prior ringing the DB. This case is managed earlier by triggering an asynchronous M3 exit via controller resume/suspend callbacks, that in turn will cause M0 transition and DB update. So, since it's not an error but just delaying of doorbell update, there is no reason to return an error. This also fixes a use after free error for skb case, indeed a caller queuing skb will try to free the skb if the queueing fails, but in that case queueing has been done.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: a8f75cb348fd52e7a5cf25991cdf9c89fb0cfd41 , < a99b661c3187365f81026d89b1133a76cd2652b3 (git)
Affected: a8f75cb348fd52e7a5cf25991cdf9c89fb0cfd41 , < 0ecc1c70dcd32c0f081b173a1a5d89952686f271 (git)
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Linux Linux Affected: 5.12
Unaffected: 0 , < 5.12 (semver)
Unaffected: 5.12.3 , ≤ 5.12.* (semver)
Unaffected: 5.13 , ≤ * (original_commit_for_fix)
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      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"https://git.kernel.org/stable/c/a99b661c3187365f81026d89b1133a76cd2652b3\", \"tags\": [\"x_transferred\"]}, {\"url\": \"https://git.kernel.org/stable/c/0ecc1c70dcd32c0f081b173a1a5d89952686f271\", \"tags\": [\"x_transferred\"]}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2024-08-04T05:17:42.873Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2021-46969\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2024-09-10T16:01:28.491057Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2024-09-11T12:42:18.501Z\"}}], \"cna\": {\"title\": \"bus: mhi: core: Fix invalid error returning in mhi_queue\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 7.8, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:L - The vulnerability is reached by transmitting through local MHI client paths (mhi_net ndo_start_xmit or AF_QIPCRTR \\u2192 qrtr_mhi xmit \\u2192 mhi_queue_skb), which require local process access to a PCIe WWAN/MHI device interface rather than remote packet parsing.\\nAC:L - With MHI PCI runtime autosuspend (2s), M3 is a normal idle state the attacker can wait for and then reliably trigger by sending traffic; no attacker-uncontrollable condition is required.\\nPR:L - An unprivileged local user can open AF_QIPCRTR sockets (no capability required for ephemeral ports) or send packets via an already-up MHI WWAN netdev route; CAP_NET_ADMIN is not required for the vulnerable queue path itself.\\nUI:N - Exploitation requires only attacker-initiated transmit while the modem is suspended; no separate victim user action is needed.\\nS:U - Impact is confined to the host kernel\u0027s memory/process security authority (standard local privilege-escalation UAF), with no VM/IOMMU/sandbox boundary crossed.\\nC:H - The skb remains referenced in the MHI transfer ring after the caller frees it, yielding a classic heap UAF that can be reclaimed/sprayed to obtain arbitrary kernel read primitives.\\nI:H - The same skb UAF/double-free on completion (e.g. mhi_net_ul_callback / qrtr ul_callback consuming the freed skb) enables heap corruption and control-flow hijacking for arbitrary write/code execution.\\nA:H - Use-after-free and double-free of the queued skb reliably cause kernel oops/panic when the deferred doorbell/completion path runs after M3 exit.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"a8f75cb348fd52e7a5cf25991cdf9c89fb0cfd41\", \"lessThan\": \"a99b661c3187365f81026d89b1133a76cd2652b3\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"a8f75cb348fd52e7a5cf25991cdf9c89fb0cfd41\", \"lessThan\": \"0ecc1c70dcd32c0f081b173a1a5d89952686f271\", \"versionType\": \"git\"}], \"programFiles\": [\"drivers/bus/mhi/core/main.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5.12\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"5.12\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.12.3\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.12.*\"}, {\"status\": \"unaffected\", \"version\": \"5.13\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"drivers/bus/mhi/core/main.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/a99b661c3187365f81026d89b1133a76cd2652b3\"}, {\"url\": \"https://git.kernel.org/stable/c/0ecc1c70dcd32c0f081b173a1a5d89952686f271\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbus: mhi: core: Fix invalid error returning in mhi_queue\\n\\nmhi_queue returns an error when the doorbell is not accessible in\\nthe current state. This can happen when the device is in non M0\\nstate, like M3, and needs to be waken-up prior ringing the DB. This\\ncase is managed earlier by triggering an asynchronous M3 exit via\\ncontroller resume/suspend callbacks, that in turn will cause M0\\ntransition and DB update.\\n\\nSo, since it\u0027s not an error but just delaying of doorbell update, there\\nis no reason to return an error.\\n\\nThis also fixes a use after free error for skb case, indeed a caller\\nqueuing skb will try to free the skb if the queueing fails, but in\\nthat case queueing has been done.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.12.3\", \"versionStartIncluding\": \"5.12\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.13\", \"versionStartIncluding\": \"5.12\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T08:45:18.172Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-46969\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T08:45:18.172Z\", \"dateReserved\": \"2024-02-27T18:42:55.943Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-02-27T18:47:05.463Z\", \"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.