CVE-2026-23472 (GCVE-0-2026-23472)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-04-06 06:59
VLAI?
Title
serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN
Summary
In the Linux kernel, the following vulnerability has been resolved: serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN uart_write_room() and uart_write() behave inconsistently when xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized): - uart_write_room() returns kfifo_avail() which can be > 0 - uart_write() checks xmit_buf and returns 0 if NULL This inconsistency causes an infinite loop in drivers that rely on tty_write_room() to determine if they can write: while (tty_write_room(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits } For example, caif_serial's handle_tx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs. Fix by making uart_write_room() also check xmit_buf and return 0 if it's NULL, consistent with uart_write(). Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < efe85a557186b7fe915572ae93a8f3f78bfd9a22 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 455ce986fa356ff43a43c0d363ba95fa152f21d5 (git)
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    Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc5 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "drivers/tty/serial/serial_core.c"
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN\n\nuart_write_room() and uart_write() behave inconsistently when\nxmit_buf is NULL (which happens for PORT_UNKNOWN ports that were\nnever properly initialized):\n\n- uart_write_room() returns kfifo_avail() which can be \u003e 0\n- uart_write() checks xmit_buf and returns 0 if NULL\n\nThis inconsistency causes an infinite loop in drivers that rely on\ntty_write_room() to determine if they can write:\n\n  while (tty_write_room(tty) \u003e 0) {\n      written = tty-\u003eops-\u003ewrite(...);\n      // written is always 0, loop never exits\n  }\n\nFor example, caif_serial\u0027s handle_tx() enters an infinite loop when\nused with PORT_UNKNOWN serial ports, causing system hangs.\n\nFix by making uart_write_room() also check xmit_buf and return 0 if\nit\u0027s NULL, consistent with uart_write().\n\nReproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13"
        }
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      "providerMetadata": {
        "dateUpdated": "2026-04-06T06:59:49.115Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/efe85a557186b7fe915572ae93a8f3f78bfd9a22"
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          "url": "https://git.kernel.org/stable/c/bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c"
        },
        {
          "url": "https://git.kernel.org/stable/c/455ce986fa356ff43a43c0d363ba95fa152f21d5"
        }
      ],
      "title": "serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23472",
    "datePublished": "2026-04-03T15:15:51.209Z",
    "dateReserved": "2026-01-13T15:37:46.022Z",
    "dateUpdated": "2026-04-06T06:59:49.115Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23472\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-03T16:16:34.977\",\"lastModified\":\"2026-04-07T13:20:55.200\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nserial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN\\n\\nuart_write_room() and uart_write() behave inconsistently when\\nxmit_buf is NULL (which happens for PORT_UNKNOWN ports that were\\nnever properly initialized):\\n\\n- uart_write_room() returns kfifo_avail() which can be \u003e 0\\n- uart_write() checks xmit_buf and returns 0 if NULL\\n\\nThis inconsistency causes an infinite loop in drivers that rely on\\ntty_write_room() to determine if they can write:\\n\\n  while (tty_write_room(tty) \u003e 0) {\\n      written = tty-\u003eops-\u003ewrite(...);\\n      // written is always 0, loop never exits\\n  }\\n\\nFor example, caif_serial\u0027s handle_tx() enters an infinite loop when\\nused with PORT_UNKNOWN serial ports, causing system hangs.\\n\\nFix by making uart_write_room() also check xmit_buf and return 0 if\\nit\u0027s NULL, consistent with uart_write().\\n\\nReproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/455ce986fa356ff43a43c0d363ba95fa152f21d5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/efe85a557186b7fe915572ae93a8f3f78bfd9a22\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • 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.
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