Vulnerability-Lookup

GHSA-FPVH-P63V-QP88

Vulnerability from github – Published: 2026-08-22 18:30 – Updated: 2026-08-27 15:31

Details

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

serial: qcom-geni: fix TX DMA buffer flush

When transmit flushing a qcom-geni UART during an ongoing TX DMA, the UART gets stuck infinitely repeating corrupted TX DMA frames.

The DMA-mode uart_ops does not provide a flush_buffer callback, so an in-flight transfer can complete after serial core has reset the transmit kfifo, underflowing its length and resubmitting page-sized transfers indefinitely. Add one that stops the transfer and clears tx_remaining and tx_queued.

The stop path was also broken: it unmapped the buffer while the serial engine could still read it, and never reset the TX DMA state machine. Cancel the main sequencer command first, then reset the state machine and wait for it before unmapping. Drop the early return so a pending mapping is also cleaned up when the main command is inactive.

The bug can be triggered from userspace with a large write immediately followed by TCOFLUSH. A following tcdrain will hang forever. The bug was reproduced and this fix was validated on Arduino Uno Q (QRB2210) using /dev/ttyHS1.

Severity

8.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74655"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-22T16:16:39Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: qcom-geni: fix TX DMA buffer flush\n\nWhen transmit flushing a qcom-geni UART during an ongoing TX DMA, the\nUART gets stuck infinitely repeating corrupted TX DMA frames.\n\nThe DMA-mode uart_ops does not provide a flush_buffer callback, so an\nin-flight transfer can complete after serial core has reset the transmit\nkfifo, underflowing its length and resubmitting page-sized transfers\nindefinitely. Add one that stops the transfer and clears tx_remaining\nand tx_queued.\n\nThe stop path was also broken: it unmapped the buffer while the serial\nengine could still read it, and never reset the TX DMA state machine.\nCancel the main sequencer command first, then reset the state machine\nand wait for it before unmapping. Drop the early return so a pending\nmapping is also cleaned up when the main command is inactive.\n\nThe bug can be triggered from userspace with a large write immediately\nfollowed by TCOFLUSH. A following tcdrain will hang forever. The bug was\nreproduced and this fix was validated on Arduino Uno Q (QRB2210)\nusing /dev/ttyHS1.",
  "id": "GHSA-fpvh-p63v-qp88",
  "modified": "2026-08-27T15:31:30Z",
  "published": "2026-08-22T18:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74655"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c31e2377f4c1bb110ca7f6e597b2253a7440c37"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/313ae287442e5e8d3f7b53b73f37d384bda072d0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b1801c0d40f62778b613334de5840aba10a564d5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-74655 (GCVE-0-2026-74655)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-08-27 12:39

Title

serial: qcom-geni: fix TX DMA buffer flush

Summary

In the Linux kernel, the following vulnerability has been resolved: serial: qcom-geni: fix TX DMA buffer flush When transmit flushing a qcom-geni UART during an ongoing TX DMA, the UART gets stuck infinitely repeating corrupted TX DMA frames. The DMA-mode uart_ops does not provide a flush_buffer callback, so an in-flight transfer can complete after serial core has reset the transmit kfifo, underflowing its length and resubmitting page-sized transfers indefinitely. Add one that stops the transfer and clears tx_remaining and tx_queued. The stop path was also broken: it unmapped the buffer while the serial engine could still read it, and never reset the TX DMA state machine. Cancel the main sequencer command first, then reset the state machine and wait for it before unmapping. Drop the early return so a pending mapping is also cleaned up when the main command is inactive. The bug can be triggered from userspace with a large write immediately followed by TCOFLUSH. A following tcdrain will hang forever. The bug was reproduced and this fix was validated on Arduino Uno Q (QRB2210) using /dev/ttyHS1.

Severity

8.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Assigner

Linux mitre root

References

5 references

URL	Tags
https://git.kernel.org/stable/c/1606abb7ce8c0cfef…
https://git.kernel.org/stable/c/313ae287442e5e8d3…
https://git.kernel.org/stable/c/1c31e2377f4c1bb11…
https://git.kernel.org/stable/c/b1801c0d40f62778b…
https://git.kernel.org/stable/c/e3c04834ae1ab5e9c…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < 1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf (git) Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < 313ae287442e5e8d3f7b53b73f37d384bda072d0 (git) Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < 1c31e2377f4c1bb110ca7f6e597b2253a7440c37 (git) Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < b1801c0d40f62778b613334de5840aba10a564d5 (git) Affected: 2aaa43c7077833301c237684cd7bc9ae5e3dec95 , < e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d (git)
Linux	Linux	Affected: 6.3 Unaffected: 0 , < 6.3 (semver) Unaffected: 6.6.154 , ≤ 6.6.* (semver) Unaffected: 6.12.104 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/serial/qcom_geni_serial.c"
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              "versionType": "git"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: qcom-geni: fix TX DMA buffer flush\n\nWhen transmit flushing a qcom-geni UART during an ongoing TX DMA, the\nUART gets stuck infinitely repeating corrupted TX DMA frames.\n\nThe DMA-mode uart_ops does not provide a flush_buffer callback, so an\nin-flight transfer can complete after serial core has reset the transmit\nkfifo, underflowing its length and resubmitting page-sized transfers\nindefinitely. Add one that stops the transfer and clears tx_remaining\nand tx_queued.\n\nThe stop path was also broken: it unmapped the buffer while the serial\nengine could still read it, and never reset the TX DMA state machine.\nCancel the main sequencer command first, then reset the state machine\nand wait for it before unmapping. Drop the early return so a pending\nmapping is also cleaned up when the main command is inactive.\n\nThe bug can be triggered from userspace with a large write immediately\nfollowed by TCOFLUSH. A following tcdrain will hang forever. The bug was\nreproduced and this fix was validated on Arduino Uno Q (QRB2210)\nusing /dev/ttyHS1."
        }
      ],
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        {
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            "baseSeverity": "HIGH",
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          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires local write(2) and tcflush(TCOFLUSH)/tcdrain() ioctls on a Qualcomm GENI DMA UART (/dev/ttyHS*), reachable only through local TTY device-node syscalls, not over a network protocol.\nAC:L - The attacker fully controls timing by issuing a large write during active TX DMA immediately followed by TCOFLUSH; no races or external victim state beyond concurrent DMA completion are required to reproduce the hang and DMA loop.\nPR:L - Triggering the bug needs only permission to open, write, and ioctl an assigned ttyHS serial port (typically dialout-group or embedded-app access on Qualcomm/Android/IoT targets), not init-namespace root or CAP_SYS_ADMIN.\nUI:N - No victim interaction is required; the attacker directly drives the vulnerable flush path with their own write and TCOFLUSH/tcdrain calls on the serial device they already control.\nS:C - The flawed stop path unmaps the TX DMA buffer while the GENI engine can still read it and without resetting the TX DMA FSM, crossing the kernel/DMA hardware memory boundary and allowing the device to access host memory outside the intended mapping.\nC:H - Stale page-sized DMA retransmissions can leak residual kernel data from the UART xmit buffer and adjacent heap, and post-unmap DMA reads can expose arbitrary remapped physical memory to the serial line or driver state.\nI:H - Missing flush handling leaves tx_remaining/tx_dma_addr inconsistent with a reset kfifo, enabling kfifo pointer underflow and uncontrolled DMA from wrong offsets that corrupt kernel memory and driver bookkeeping.\nA:H - The UART enters an infinite loop of corrupted TX DMA frames and tcdrain/tty_wait_until_sent never completes, causing permanent hang of processes draining the port and sustained denial of the serial subsystem."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T12:39:56.189Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf"
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        },
        {
          "url": "https://git.kernel.org/stable/c/e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d"
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      "title": "serial: qcom-geni: fix TX DMA buffer flush",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74655",
    "datePublished": "2026-08-22T15:32:29.993Z",
    "dateReserved": "2026-08-15T05:44:03.923Z",
    "dateUpdated": "2026-08-27T12:39:56.189Z",
    "state": "PUBLISHED"
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}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-FPVH-P63V-QP88

CVE-2026-74655 (GCVE-0-2026-74655)

Tags

Sightings

Nomenclature