{"id":"CVE-2024-35929","summary":"rcu/nocb: Fix WARN_ON_ONCE() in the rcu_nocb_bypass_lock()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nrcu/nocb: Fix WARN_ON_ONCE() in the rcu_nocb_bypass_lock()\n\nFor the kernels built with CONFIG_RCU_NOCB_CPU_DEFAULT_ALL=y and\nCONFIG_RCU_LAZY=y, the following scenarios will trigger WARN_ON_ONCE()\nin the rcu_nocb_bypass_lock() and rcu_nocb_wait_contended() functions:\n\n        CPU2                                               CPU11\nkthread\nrcu_nocb_cb_kthread                                       ksys_write\nrcu_do_batch                                              vfs_write\nrcu_torture_timer_cb                                      proc_sys_write\n__kmem_cache_free                                         proc_sys_call_handler\nkmemleak_free                                             drop_caches_sysctl_handler\ndelete_object_full                                        drop_slab\n__delete_object                                           shrink_slab\nput_object                                                lazy_rcu_shrink_scan\ncall_rcu                                                  rcu_nocb_flush_bypass\n__call_rcu_commn                                            rcu_nocb_bypass_lock\n                                                            raw_spin_trylock(&rdp-\u003enocb_bypass_lock) fail\n                                                            atomic_inc(&rdp-\u003enocb_lock_contended);\nrcu_nocb_wait_contended                                     WARN_ON_ONCE(smp_processor_id() != rdp-\u003ecpu);\n WARN_ON_ONCE(atomic_read(&rdp-\u003enocb_lock_contended))                                          |\n                            |_ _ _ _ _ _ _ _ _ _same rdp and rdp-\u003ecpu != 11_ _ _ _ _ _ _ _ _ __|\n\nReproduce this bug with \"echo 3 \u003e /proc/sys/vm/drop_caches\".\n\nThis commit therefore uses rcu_nocb_try_flush_bypass() instead of\nrcu_nocb_flush_bypass() in lazy_rcu_shrink_scan().  If the nocb_bypass\nqueue is being flushed, then rcu_nocb_try_flush_bypass will return\ndirectly.","modified":"2026-04-02T11:52:23.992967Z","published":"2024-05-19T10:10:38.388Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35929.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/4d58c9fb45c70e62c19e8be3f3605889c47601bc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/927d1f4f77e4784ab3944a9df86ab14d1cd3185a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dda98810b552fc6bf650f4270edeebdc2f28bd3f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/35xxx/CVE-2024-35929.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-35929"},{"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":"7625926086765123251f765d91fc3a70617d334d"},{"fixed":"4d58c9fb45c70e62c19e8be3f3605889c47601bc"},{"fixed":"927d1f4f77e4784ab3944a9df86ab14d1cd3185a"},{"fixed":"dda98810b552fc6bf650f4270edeebdc2f28bd3f"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-35929.json"}}],"schema_version":"1.7.5"}