{"id":"CVE-2026-72069","summary":"locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nlocking/rt: Fix the incorrect RCU protection in rt_spin_unlock()\n\nrt_spin_unlock() releases the RCU protection before unlocking the\nlock. That opens the door for the following UAF scenario:\n\n T1\t\t\t\t\tT2\n spin_lock(&p-\u003elock);\t\trcu_read_lock();\n invalidate(p);\t\t\tp = rcu_dereference(ptr);\n rcu_assign_pointer(ptr, NULL);\tif (!p) return;\n spin_unlock(&p-\u003elock);\t\tspin_lock(&p-\u003elock)\n \t\t\t\t   lock(&lock-\u003elock);\n\t\t\t\t   rcu_read_lock();\n kfree_rcu(p);\t\t\trcu_read_unlock();\n\t\t\t\t....\n\t\t\t\tspin_unlock(&p-\u003elock)\n\t\t\t\t  rcu_read_unlock(); // Ends grace period\n rcu_do_batch()\n   kfree(p);\n\t\t\t    UAF -\u003e\t  rt_mutex_cmpxchg_release(&lock-\u003elock...)\n\nRegular spinlocks keep preemption disabled accross the unlock operation,\nwhich provides full RCU protection, but the RT substitution fails to\nresemble that. Same applies for the rwlock substitution.\n\nMove the rcu_read_unlock() invocation past the unlock operations to match\nthe non-RT semantics. This makes it asymmetric vs. rt_xxx_lock(), but\nthat's harmless as the caller needs to hold RCU read lock across the lock\noperation. The migrate_enable() call stays before the unlock operation\nbecause there is no per CPU operation in the unlock path which would\nrequire migration to be kept disabled.","modified":"2026-08-24T03:47:34.994485697Z","published":"2026-08-15T05:52:21.752Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72069.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1f0d56d3f1e88f20f6e46109402f8c15d59bac37"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3cfaac77b3c32ac3940df28866de263c3f45d24c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/633cadbc0b8323f5cc140a285d2432089dbb534e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/83f9fb561c1c3917e19f95523dd933c7d30291aa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/89038cc87d80c77e7aa6f42a64b2573b74af339f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9d1fcd64ab81200e02b7a6db5eb1da8e244e8289"},{"type":"WEB","url":"https://git.kernel.org/stable/c/af28d801cd2db4cc7378554499bd4a5d84a5517e"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72069.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72069"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0f383b6dc96e976dfbf2721b0bf10bd96103b341"},{"fixed":"af28d801cd2db4cc7378554499bd4a5d84a5517e"},{"fixed":"9d1fcd64ab81200e02b7a6db5eb1da8e244e8289"},{"fixed":"3cfaac77b3c32ac3940df28866de263c3f45d24c"},{"fixed":"1f0d56d3f1e88f20f6e46109402f8c15d59bac37"},{"fixed":"633cadbc0b8323f5cc140a285d2432089dbb534e"},{"fixed":"83f9fb561c1c3917e19f95523dd933c7d30291aa"},{"fixed":"89038cc87d80c77e7aa6f42a64b2573b74af339f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72069.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.15.0"},{"fixed":"5.15.217"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.184"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72069.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}