GHSA-C3RF-2Q38-4HG9

Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 15:31
VLAI
Details

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

net/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks()

rds_tcp_reset_callbacks() quiesces the transmit path by setting the path state to RDS_CONN_RESETTING and then waiting for RDS_IN_XMIT to be sampled clear before swapping the underlying socket and calling rds_send_path_reset().

Sampling the bit clear is not the same as owning it: rds_send_xmit() can re-acquire RDS_IN_XMIT right after the wait_event() returns. Its state recheck after taking the lock is a store-buffering pattern (the resetter writes the state and reads the bit, the sender writes the bit and reads the state) and acquire_in_xmit() is only an acquire operation, so on weakly ordered architectures both sides can miss each other's write and the transmit path then runs concurrently with rds_send_path_reset() rewriting cp_xmit_* state - which is exactly what the comment above rds_send_path_reset() tells its callers to prevent.

Take the lock instead, hold it across the socket swap and rds_send_path_reset(), and release it with a wake-up at the end. The lock-ordering constraint documented above the wait still holds: the lock is acquired before lock_sock(), so a sender inside tcp_sendmsg() can never be waited on while we hold the socket lock.

Two details of the old code go away with the same change:

  • t_sock is now read only after the lock is acquired. The old code cached it before waiting; the teardown in rds_conn_shutdown() releases that socket and clears t_sock, so a pointer cached before the wait can be stale by the time the accept path resumes. Reading it under RDS_IN_XMIT is what makes the exclusion complete once the teardown owns the same lock, which the next patch arranges; until then the teardown still only samples the bit, and the two paths remain as exposed to each other as they are today.

  • The old !osock early path called rds_send_path_reset() with no serialization at all. It now runs under the lock like the normal path. The conditional RDS_CONN_RESETTING transition of the previous patch happens before the socket check either way: a path found without a socket is either still connecting (its reconnect worker blocked on t_conn_path_lock) and legitimately goes RESETTING -> UP on the new socket, or it has been torn down meanwhile and is dropped.

The in-function comment describing the old wait-based quiesce is rewritten to describe the lock-based one, and the stale block comment above the function (which still described a return value and an incomplete list of t_sock writers) is refreshed to name all four writers - the connect, accept, teardown and swap paths - and what serializes each of them.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-98070"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-25T11:17:36Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks()\n\nrds_tcp_reset_callbacks() quiesces the transmit path by setting the\npath state to RDS_CONN_RESETTING and then waiting for RDS_IN_XMIT to\nbe sampled clear before swapping the underlying socket and calling\nrds_send_path_reset().\n\nSampling the bit clear is not the same as owning it: rds_send_xmit()\ncan re-acquire RDS_IN_XMIT right after the wait_event() returns.  Its\nstate recheck after taking the lock is a store-buffering pattern (the\nresetter writes the state and reads the bit, the sender writes the\nbit and reads the state) and acquire_in_xmit() is only an acquire\noperation, so on weakly ordered architectures both sides can miss\neach other\u0027s write and the transmit path then runs concurrently with\nrds_send_path_reset() rewriting cp_xmit_* state - which is exactly\nwhat the comment above rds_send_path_reset() tells its callers to\nprevent.\n\nTake the lock instead, hold it across the socket swap and\nrds_send_path_reset(), and release it with a wake-up at the end.  The\nlock-ordering constraint documented above the wait still holds: the\nlock is acquired before lock_sock(), so a sender inside tcp_sendmsg()\ncan never be waited on while we hold the socket lock.\n\nTwo details of the old code go away with the same change:\n\n - t_sock is now read only after the lock is acquired.  The old code\n   cached it before waiting; the teardown in rds_conn_shutdown()\n   releases that socket and clears t_sock, so a pointer cached before\n   the wait can be stale by the time the accept path resumes.  Reading\n   it under RDS_IN_XMIT is what makes the exclusion complete once the\n   teardown owns the same lock, which the next patch arranges; until\n   then the teardown still only samples the bit, and the two paths\n   remain as exposed to each other as they are today.\n\n - The old !osock early path called rds_send_path_reset() with no\n   serialization at all.  It now runs under the lock like the normal\n   path.  The conditional RDS_CONN_RESETTING transition of the\n   previous patch happens before the socket check either way: a path\n   found without a socket is either still connecting (its reconnect\n   worker blocked on t_conn_path_lock) and legitimately goes\n   RESETTING -\u003e UP on the new socket, or it has been torn down\n   meanwhile and is dropped.\n\nThe in-function comment describing the old wait-based quiesce is\nrewritten to describe the lock-based one, and the stale block comment\nabove the function (which still described a return value and an\nincomplete list of t_sock writers) is refreshed to name all four\nwriters - the connect, accept, teardown and swap paths - and what\nserializes each of them.",
  "id": "GHSA-c3rf-2q38-4hg9",
  "modified": "2026-09-25T15:31:44Z",
  "published": "2026-09-25T12:31:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98070"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/02c5f9dc2efd823e061954d564ce00bacd1bebeb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/062d9e008c67289e8e1b221ecdd8f9d60566d012"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8e4c3b7844c906c7097b4cfedd9dd1f48c9a6a92"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d625112564c3e980e02504270222b49b82690cee"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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