{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-45949", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-13T15:03:33.088Z", "datePublished": "2026-05-27T12:18:05.718Z", "dateUpdated": "2026-10-21T12:41:05.248Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:41:05.248Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwrng: core - use RCU and work_struct to fix race condition\n\nCurrently, hwrng_fill is not cleared until the hwrng_fillfn() thread\nexits. Since hwrng_unregister() reads hwrng_fill outside the rng_mutex\nlock, a concurrent hwrng_unregister() may call kthread_stop() again on\nthe same task.\n\nAdditionally, if hwrng_unregister() is called immediately after\nhwrng_register(), the stopped thread may have never been executed. Thus,\nhwrng_fill remains dirty even after hwrng_unregister() returns. In this\ncase, subsequent calls to hwrng_register() will fail to start new\nthreads, and hwrng_unregister() will call kthread_stop() on the same\nfreed task. In both cases, a use-after-free occurs:\n\nrefcount_t: addition on 0; use-after-free.\nWARNING: ... at lib/refcount.c:25 refcount_warn_saturate+0xec/0x1c0\nCall Trace:\n kthread_stop+0x181/0x360\n hwrng_unregister+0x288/0x380\n virtrng_remove+0xe3/0x200\n\nThis patch fixes the race by protecting the global hwrng_fill pointer\ninside the rng_mutex lock, so that hwrng_fillfn() thread is stopped only\nonce, and calls to kthread_run() and kthread_stop() are serialized\nwith the lock held.\n\nTo avoid deadlock in hwrng_fillfn() while being stopped with the lock\nheld, we convert current_rng to RCU, so that get_current_rng() can read\ncurrent_rng without holding the lock. To remove the lock from put_rng(),\nwe also delay the actual cleanup into a work_struct.\n\nSince get_current_rng() no longer returns ERR_PTR values, the IS_ERR()\nchecks are removed from its callers.\n\nWith hwrng_fill protected by the rng_mutex lock, hwrng_fillfn() can no\nlonger clear hwrng_fill itself. Therefore, if hwrng_fillfn() returns\ndirectly after current_rng is dropped, kthread_stop() would be called on\na freed task_struct later. To fix this, hwrng_fillfn() calls schedule()\nnow to keep the task alive until being stopped. The kthread_stop() call\nis also moved from hwrng_unregister() to drop_current_rng(), ensuring\nkthread_stop() is called on all possible paths where current_rng becomes\nNULL, so that the thread would not wait forever." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/char/hw_random/core.c", "include/linux/hw_random.h" ], "versions": [ { "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347", "lessThan": "1cde96d5d53b9105b48617afbc4682a83db4ff04", "status": "affected", "versionType": "git" }, { "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347", "lessThan": "d5b7730f06994499632026c30e38e0317c4569e2", "status": "affected", "versionType": "git" }, { "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347", "lessThan": "dcf416eb88eafe1e3c0f920a14bdffd10bc4d259", "status": "affected", "versionType": "git" }, { "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347", "lessThan": "ad38f2cdfef9a2f2899c30cad269baec5bfd4a5d", "status": "affected", "versionType": "git" }, { "version": "be4000bc4644d027c519b6361f5ae3bbfc52c347", "lessThan": "cc2f39d6ac48e6e3cb2d6240bc0d6df839dd0828", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/char/hw_random/core.c", "include/linux/hw_random.h" ], "versions": [ { "version": "3.17", "status": "affected" }, { "version": "0", "lessThan": "3.17", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.75", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.14", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.4", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.17", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.17", "versionEndExcluding": "6.12.75" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.17", "versionEndExcluding": "6.18.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.17", "versionEndExcluding": "6.19.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.17", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/1cde96d5d53b9105b48617afbc4682a83db4ff04" }, { "url": "https://git.kernel.org/stable/c/d5b7730f06994499632026c30e38e0317c4569e2" }, { "url": "https://git.kernel.org/stable/c/dcf416eb88eafe1e3c0f920a14bdffd10bc4d259" }, { "url": "https://git.kernel.org/stable/c/ad38f2cdfef9a2f2899c30cad269baec5bfd4a5d" }, { "url": "https://git.kernel.org/stable/c/cc2f39d6ac48e6e3cb2d6240bc0d6df839dd0828" } ], "title": "hwrng: core - use RCU and work_struct to fix race condition", "x_generator": { "engine": "bippy-1.2.0" } } } }