{"id":"AZL-52494","summary":"CVE-2024-50121 affecting package kernel for versions less than 6.6.64.2-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: cancel nfsd_shrinker_work using sync mode in nfs4_state_shutdown_net\n\nIn the normal case, when we excute `echo 0 \u003e /proc/fs/nfsd/threads`, the\nfunction `nfs4_state_destroy_net` in `nfs4_state_shutdown_net` will\nrelease all resources related to the hashed `nfs4_client`. If the\n`nfsd_client_shrinker` is running concurrently, the `expire_client`\nfunction will first unhash this client and then destroy it. This can\nlead to the following warning. Additionally, numerous use-after-free\nerrors may occur as well.\n\nnfsd_client_shrinker         echo 0 \u003e /proc/fs/nfsd/threads\n\nexpire_client                nfsd_shutdown_net\n  unhash_client                ...\n                               nfs4_state_shutdown_net\n                                 /* won't wait shrinker exit */\n  /*                             cancel_work(&nn-\u003enfsd_shrinker_work)\n   * nfsd_file for this          /* won't destroy unhashed client1 */\n   * client1 still alive         nfs4_state_destroy_net\n   */\n\n                               nfsd_file_cache_shutdown\n                                 /* trigger warning */\n                                 kmem_cache_destroy(nfsd_file_slab)\n                                 kmem_cache_destroy(nfsd_file_mark_slab)\n  /* release nfsd_file and mark */\n  __destroy_client\n\n====================================================================\nBUG nfsd_file (Not tainted): Objects remaining in nfsd_file on\n__kmem_cache_shutdown()\n--------------------------------------------------------------------\nCPU: 4 UID: 0 PID: 764 Comm: sh Not tainted 6.12.0-rc3+ #1\n\n dump_stack_lvl+0x53/0x70\n slab_err+0xb0/0xf0\n __kmem_cache_shutdown+0x15c/0x310\n kmem_cache_destroy+0x66/0x160\n nfsd_file_cache_shutdown+0xac/0x210 [nfsd]\n nfsd_destroy_serv+0x251/0x2a0 [nfsd]\n nfsd_svc+0x125/0x1e0 [nfsd]\n write_threads+0x16a/0x2a0 [nfsd]\n nfsctl_transaction_write+0x74/0xa0 [nfsd]\n vfs_write+0x1a5/0x6d0\n ksys_write+0xc1/0x160\n do_syscall_64+0x5f/0x170\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n====================================================================\nBUG nfsd_file_mark (Tainted: G    B   W         ): Objects remaining\nnfsd_file_mark on __kmem_cache_shutdown()\n--------------------------------------------------------------------\n\n dump_stack_lvl+0x53/0x70\n slab_err+0xb0/0xf0\n __kmem_cache_shutdown+0x15c/0x310\n kmem_cache_destroy+0x66/0x160\n nfsd_file_cache_shutdown+0xc8/0x210 [nfsd]\n nfsd_destroy_serv+0x251/0x2a0 [nfsd]\n nfsd_svc+0x125/0x1e0 [nfsd]\n write_threads+0x16a/0x2a0 [nfsd]\n nfsctl_transaction_write+0x74/0xa0 [nfsd]\n vfs_write+0x1a5/0x6d0\n ksys_write+0xc1/0x160\n do_syscall_64+0x5f/0x170\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nTo resolve this issue, cancel `nfsd_shrinker_work` using synchronous\nmode in nfs4_state_shutdown_net.","modified":"2026-04-01T05:17:51.159824Z","published":"2024-11-05T18:15:15Z","upstream":["CVE-2024-50121"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-50121"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.64.2-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-52494.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}