Skip to content
Heist/ feed
Unrated

hwrng: core - use RCU and work_struct to fix race condition

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: hwrng: core - use RCU and work_struct to fix race condition Currently, hwrng_fill is not cleared until the hwrng_fillfn() thread exits. Since hwrng_unregister() reads hwrng_fill outside the rng_mutex lock, a concurrent hwrng_unregister() may call kthread_stop() again on the same task. Additionally, if hwrng_unregister() is called immediately after hwrng_register(), the stopped thread may have never been executed. Thus, hwrng_fill remains dirty even after hwrng_unregister() returns. In this case, subsequent calls to hwrng_register() will fail to start new threads, and hwrng_unregister() will call kthread_stop() on the same freed task. In both cases, a use-after-free occurs: refcount_t: addition on 0; use-after-free. WARNING: ... at lib/refcount.c:25 refcount_warn_saturate+0xec/0x1c0 Call Trace: kthread_stop+0x181/0x360 hwrng_unregister+0x288/0x380 virtrng_remove+0xe3/0x200 This patch fixes the race by protecting the global hwrng_fill pointer inside the rng_mutex lock, so that hwrng_fillfn() thread is stopped only once, and calls to kthread_run() and kthread_stop() are serialized with the lock held. To avoid deadlock in hwrng_fillfn() while being stopped with the lock held, we convert current_rng to RCU, so that get_current_rng() can read current_rng without holding the lock. To remove the lock from put_rng(), we also delay the actual cleanup into a work_struct. Since get_current_rng() no longer returns ERR_PTR

Announced Source revision 1
Original source ↗

CVE-2026-45949

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-2026-45949

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": "be4000bc4644d027c519b6361f5ae3bbfc52c347",
        "lessThan": "1cde96d5d53b9105b48617afbc4682a83db4ff04",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347",
        "lessThan": "d5b7730f06994499632026c30e38e0317c4569e2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347",
        "lessThan": "dcf416eb88eafe1e3c0f920a14bdffd10bc4d259",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347",
        "lessThan": "ad38f2cdfef9a2f2899c30cad269baec5bfd4a5d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347",
        "lessThan": "cc2f39d6ac48e6e3cb2d6240bc0d6df839dd0828",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/char/hw_random/core.c",
      "include/linux/hw_random.h"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.17"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.17",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.75",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.14",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.4",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/char/hw_random/core.c",
      "include/linux/hw_random.h"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-45949

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#46315 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement