{"id":"CVE-2021-47507","state":"PUBLISHED","title":"nfsd: Fix nsfd startup race (again)","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: Fix nsfd startup race (again)\n\nCommit bd5ae9288d64 (\"nfsd: register pernet ops last, unregister first\")\nhas re-opened rpc_pipefs_event() race against nfsd_net_id registration\n(register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76\n(\"nfsd: fix nsfd startup race triggering BUG_ON\").\n\nRestore the order of register_pernet_subsys() vs register_cld_notifier().\nAdd WARN_ON() to prevent a future regression.\n\nCrash info:\nUnable to handle kernel NULL pointer dereference at virtual address 0000000000000012\nCPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1\npc : rpc_pipefs_event+0x54/0x120 [nfsd]\nlr : rpc_pipefs_event+0x48/0x120 [nfsd]\nCall trace:\n rpc_pipefs_event+0x54/0x120 [nfsd]\n blocking_notifier_call_chain\n rpc_fill_super\n get_tree_keyed\n rpc_fs_get_tree\n vfs_get_tree\n do_mount\n ksys_mount\n __arm64_sys_mount\n el0_svc_handler\n el0_svc","publishedAt":"2024-05-24T15:01:53.401Z","updatedAt":"2026-05-23T15:20:06.443Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8677e99150b0830d29cc1318b4cc559e176940bb","status":"affected","lessThan":"f5734b1714ca355703e9ea8fb61d04beff1790b9","versionType":"git"},{"version":"7c7cb07d4affcf41749234fe9dc4d90cd3959e32","status":"affected","lessThan":"c520943a00ad5015704969ad3304c956bcd49d25","versionType":"git"},{"version":"bd5ae9288d6451bd346a1b4a59d4fe7e62ba29b7","status":"affected","lessThan":"8bf902fee5893cfc2f04a698abab47629699ae9a","versionType":"git"},{"version":"bd5ae9288d6451bd346a1b4a59d4fe7e62ba29b7","status":"affected","lessThan":"b10252c7ae9c9d7c90552f88b544a44ee773af64","versionType":"git"},{"version":"4d41f65efeec0a6da6088341203c81e49ebfcd90","status":"affected","versionType":"git"},{"version":"5.4.102","status":"affected","lessThan":"5.4.165","versionType":"semver"},{"version":"5.10.20","status":"affected","lessThan":"5.10.85","versionType":"semver"},{"version":"5.11.3","status":"affected","lessThan":"5.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4recover.c","fs/nfsd/nfsctl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"5.4.165","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.85","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.8","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4recover.c","fs/nfsd/nfsctl.c"]}],"references":["https://git.kernel.org/stable/c/f5734b1714ca355703e9ea8fb61d04beff1790b9","https://git.kernel.org/stable/c/c520943a00ad5015704969ad3304c956bcd49d25","https://git.kernel.org/stable/c/8bf902fee5893cfc2f04a698abab47629699ae9a","https://git.kernel.org/stable/c/b10252c7ae9c9d7c90552f88b544a44ee773af64"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47507.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47507","state":"PUBLISHED","datePublished":"2024-05-24T15:01:53.401Z","dateUpdated":"2026-05-23T15:20:06.443Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-05-22T06:20:56.206Z"},"containers":{"cna":{"title":"nfsd: Fix nsfd startup race (again)","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: Fix nsfd startup race (again)\n\nCommit bd5ae9288d64 (\"nfsd: register pernet ops last, unregister first\")\nhas re-opened rpc_pipefs_event() race against nfsd_net_id registration\n(register_pernet_subsys()) which has been fixed by commit bb7ffbf29e76\n(\"nfsd: fix nsfd startup race triggering BUG_ON\").\n\nRestore the order of register_pernet_subsys() vs register_cld_notifier().\nAdd WARN_ON() to prevent a future regression.\n\nCrash info:\nUnable to handle kernel NULL pointer dereference at virtual address 0000000000000012\nCPU: 8 PID: 345 Comm: mount Not tainted 5.4.144-... #1\npc : rpc_pipefs_event+0x54/0x120 [nfsd]\nlr : rpc_pipefs_event+0x48/0x120 [nfsd]\nCall trace:\n rpc_pipefs_event+0x54/0x120 [nfsd]\n blocking_notifier_call_chain\n rpc_fill_super\n get_tree_keyed\n rpc_fs_get_tree\n vfs_get_tree\n do_mount\n ksys_mount\n 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