CVE-2026-97952 (GCVE-0-2026-97952)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:23 – Updated: 2026-09-25 10:23
VLAI
Title
sunvdc: unmap LDC cookies when the descriptor send fails
Summary
In the Linux kernel, the following vulnerability has been resolved: sunvdc: unmap LDC cookies when the descriptor send fails __send_request() maps the request's pages into the LDC channel's map table (ldc_map_sg()), fills in the descriptor and marks it VIO_DESC_READY before ringing the doorbell via __vdc_tx_trigger(). When the trigger fails, the error path only prints a message: the descriptor stays READY and the cookies are never unmapped. The mapping is normally released in vdc_end_one() when the peer completes the descriptor - but a descriptor whose doorbell was never sent will never complete, and since dr->prod is not advanced on failure, the reset path (vdc_requeue_inflight(), which walks [cons, prod)) never visits it either. The map table entries are leaked permanently. Since commit a11f6ca9aef9 ("sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN") trigger failures occur in practice under load, so every resulting I/O error also leaks one request's worth of entries from the fixed-size (8192 entries per channel) map table. Because the allocator hands out contiguous ranges, fragmentation makes large multi-segment requests fail first as the table drains, until ldc_map_sg() fails permanently and the disk is dead until reboot. It also makes any retry-based recovery unusable: requeuing the request on -EAGAIN remaps the pages on every attempt, overwriting desc->cookies and orphaning the previous mapping, so the table drains at the retry rate. This is the memory exhaustion observed when the requeue approach was first tested in October 2025. Roll back on failure: unmap the cookies, mark the descriptor FREE again and clear the request entry. If the trigger failed with -ENOTCONN, __vdc_tx_trigger() has already reset the port, which tears down and reallocates both the dring and the LDC channel including its map table - nothing to roll back, and the stale descriptor must not be touched.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a11f6ca9aef989b56cd31ff4ee2af4fb31a172ec , < ab81a5c1014a38dab0fb402609fd866b0bcb4726 (git)
Affected: a11f6ca9aef989b56cd31ff4ee2af4fb31a172ec , < 57835952566f0be9b365a6eb3a70b397a9d5ef47 (git)
Affected: a11f6ca9aef989b56cd31ff4ee2af4fb31a172ec , < f3322baa3a8ac87730feae952c1146269d78e098 (git)
Affected: a11f6ca9aef989b56cd31ff4ee2af4fb31a172ec , < 0c6da21fa35e03fc74f09895433ccd6d4a9c3530 (git)
Affected: 627e656239c63d8a81672d08de7885e89c12fa75 (git)
Affected: a1ef7d5da9b2c145f811a80bb8197df6037a7572 (git)
Affected: 7ab4b6526fdcdfa7772984bbcd2ac4fd14fa223b (git)
Affected: 3fbba4e55051d01a72b56ea192064175924bf56a (git)
Affected: 3e380fc2ae4d18210eec9c472b12e2b2544f7dc1 (git)
Affected: 4.4.175 , < 4.5 (semver)
Affected: 4.9.156 , < 4.10 (semver)
Affected: 4.14.99 , < 4.15 (semver)
Affected: 4.19.21 , < 4.20 (semver)
Affected: 4.20.8 , < 4.21 (semver)
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Linux Linux Affected: 5.0
Unaffected: 0 , < 5.0 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunvdc: unmap LDC cookies when the descriptor send fails\n\n__send_request() maps the request\u0027s pages into the LDC channel\u0027s map\ntable (ldc_map_sg()), fills in the descriptor and marks it\nVIO_DESC_READY before ringing the doorbell via __vdc_tx_trigger().\nWhen the trigger fails, the error path only prints a message: the\ndescriptor stays READY and the cookies are never unmapped. The\nmapping is normally released in vdc_end_one() when the peer completes\nthe descriptor - but a descriptor whose doorbell was never sent will\nnever complete, and since dr-\u003eprod is not advanced on failure, the\nreset path (vdc_requeue_inflight(), which walks [cons, prod)) never\nvisits it either. The map table entries are leaked permanently.\n\nSince commit a11f6ca9aef9 (\"sunvdc: Do not spin in an infinite loop\nwhen vio_ldc_send() returns EAGAIN\") trigger failures occur in\npractice under load, so every resulting I/O error also leaks one\nrequest\u0027s worth of entries from the fixed-size (8192 entries per\nchannel) map table. Because the allocator hands out contiguous\nranges, fragmentation makes large multi-segment requests fail first\nas the table drains, until ldc_map_sg() fails permanently and the\ndisk is dead until reboot.\n\nIt also makes any retry-based recovery unusable: requeuing the\nrequest on -EAGAIN remaps the pages on every attempt, overwriting\ndesc-\u003ecookies and orphaning the previous mapping, so the table\ndrains at the retry rate. This is the memory exhaustion observed\nwhen the requeue approach was first tested in October 2025.\n\nRoll back on failure: unmap the cookies, mark the descriptor FREE\nagain and clear the request entry. If the trigger failed with\n-ENOTCONN, __vdc_tx_trigger() has already reset the port, which\ntears down and reallocates both the dring and the LDC channel\nincluding its map table - nothing to roll back, and the stale\ndescriptor must not be touched."
        }
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    "datePublished": "2026-09-25T10:23:00.161Z",
    "dateReserved": "2026-09-25T10:18:58.205Z",
    "dateUpdated": "2026-09-25T10:23:00.161Z",
    "state": "PUBLISHED"
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunvdc: unmap LDC cookies when the descriptor send fails\n\n__send_request() maps the request\u0027s pages into the LDC channel\u0027s map\ntable (ldc_map_sg()), fills in the descriptor and marks it\nVIO_DESC_READY before ringing the doorbell via __vdc_tx_trigger().\nWhen the trigger fails, the error path only prints a message: the\ndescriptor stays READY and the cookies are never unmapped. The\nmapping is normally released in vdc_end_one() when the peer completes\nthe descriptor - but a descriptor whose doorbell was never sent will\nnever complete, and since dr-\u003eprod is not advanced on failure, the\nreset path (vdc_requeue_inflight(), which walks [cons, prod)) never\nvisits it either. The map table entries are leaked permanently.\n\nSince commit a11f6ca9aef9 (\"sunvdc: Do not spin in an infinite loop\nwhen vio_ldc_send() returns EAGAIN\") trigger failures occur in\npractice under load, so every resulting I/O error also leaks one\nrequest\u0027s worth of entries from the fixed-size (8192 entries per\nchannel) map table. Because the allocator hands out contiguous\nranges, fragmentation makes large multi-segment requests fail first\nas the table drains, until ldc_map_sg() fails permanently and the\ndisk is dead until reboot.\n\nIt also makes any retry-based recovery unusable: requeuing the\nrequest on -EAGAIN remaps the pages on every attempt, overwriting\ndesc-\u003ecookies and orphaning the previous mapping, so the table\ndrains at the retry rate. This is the memory exhaustion observed\nwhen the requeue approach was first tested in October 2025.\n\nRoll back on failure: unmap the cookies, mark the descriptor FREE\nagain and clear the request entry. If the trigger failed with\n-ENOTCONN, __vdc_tx_trigger() has already reset the port, which\ntears down and reallocates both the dring and the LDC channel\nincluding its map table - nothing to roll back, and the stale\ndescriptor must not be touched."
          }
        ],
        "id": "CVE-2026-97952",
        "lastModified": "2026-09-25T11:17:22.790",
        "metrics": {},
        "published": "2026-09-25T11:17:22.790",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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