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xenbus: Use kref to track req lifetime

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: xenbus: Use kref to track req lifetime Marek reported seeing a NULL pointer fault in the xenbus_thread callstack: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: e030:__wake_up_common+0x4c/0x180 Call Trace: __wake_up_common_lock+0x82/0xd0 process_msg+0x18e/0x2f0 xenbus_thread+0x165/0x1c0 process_msg+0x18e is req->cb(req). req->cb is set to xs_wake_up(), a thin wrapper around wake_up(), or xenbus_dev_queue_reply(). It seems like it was xs_wake_up() in this case. It seems like req may have woken up the xs_wait_for_reply(), which kfree()ed the req. When xenbus_thread resumes, it faults on the zero-ed data. Linux Device Drivers 2nd edition states: "Normally, a wake_up call can cause an immediate reschedule to happen, meaning that other processes might run before wake_up returns." ... which would match the behaviour observed. Change to keeping two krefs on each request. One for the caller, and one for xenbus_thread. Each will kref_put() when finished, and the last will free it. This use of kref matches the description in Documentation/core-api/kref.rst

Announced Source revision 1
Original source ↗

CVE-2025-37949

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2025-37949

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "0e94a246bb6d9538010b6c02d2b1d4717a97b2e5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "f1bcac367bc95631afbb918348f30dec887d0e1b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "4d260a5558df4650eb87bc41b2c9ac2d6b2ba447",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "8b02f85e84dc6f7c150cef40ddb69af5a25659e5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "cbfaf46b88a4c01b64c4186cdccd766c19ae644c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "8e9c8a0393b5f85f1820c565ab8105660f4e8f92",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "2466b0f66795c3c426cacc8998499f38031dbb59",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd8aa9095a95c02dcc35540a263267c29b8fda9d",
        "lessThan": "1f0304dfd9d217c2f8b04a9ef4b3258a66eedd27",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/xen/xenbus/xenbus.h",
      "drivers/xen/xenbus/xenbus_comms.c",
      "drivers/xen/xenbus/xenbus_dev_frontend.c",
      "drivers/xen/xenbus/xenbus_xs.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.11"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.11",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.4.294",
        "versionType": "semver",
        "lessThanOrEqual": "5.4.*"
      },
      {
        "status": "unaffected",
        "version": "5.10.238",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.183",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.139",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.91",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.29",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.14.7",
        "versionType": "semver",
        "lessThanOrEqual": "6.14.*"
      },
      {
        "status": "unaffected",
        "version": "6.15",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/xen/xenbus/xenbus.h",
      "drivers/xen/xenbus/xenbus_comms.c",
      "drivers/xen/xenbus/xenbus_dev_frontend.c",
      "drivers/xen/xenbus/xenbus_xs.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2025-37949

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#30498 · Revision 1
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Publisher date
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