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