{"id":"CVE-2026-89714","state":"PUBLISHED","title":"NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails\n\nnfs4_server_common_setup() allocates server->delegation_hash_table\nfirst, but server->destroy - the only path that frees the table via\nnfs4_destroy_server() - is not assigned until the very end of the\nfunction. If any intermediate step fails (the is_ds_only_client()\ncheck, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),\nthe function returns with server->destroy still NULL, so the caller's\nnfs_free_server() skips the destroy callback and the hash table is\nleaked (4 KiB per attempt with the default delegation watermark).\n\nThis is trivially reachable from userspace: every failed NFSv4 mount\nleaks one allocation. A client that persistently retries a mount that\ncannot succeed leaks kernel memory without bound. Observed in\nproduction where a Longhorn backup poller retried mount.nfs4 against\nan NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of\nunreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated\n12 GiB of leaked slab before the source was identified via the\nkmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).\n\nReproducer:\n\n  # server exports NFSv3 only (or export path absent for v4)\n  while :; do mount -t nfs4 <server>:/missing /mnt; done\n  # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration\n\nFree the table on the error paths between the allocation and the\nassignment of server->destroy.","publishedAt":"2026-09-11T19:46:28.476Z","updatedAt":"2026-10-19T08:51:27.182Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f5b3108e6a14418b120a3c38ca589b8d6cf87627","status":"affected","lessThan":"f3adf1643517357221422c05986d6de5df7b9913","versionType":"git"},{"version":"f5b3108e6a14418b120a3c38ca589b8d6cf87627","status":"affected","lessThan":"0fd2b9687dae36be5b84eab39b4c627bb7ab33b3","versionType":"git"},{"version":"f5b3108e6a14418b120a3c38ca589b8d6cf87627","status":"affected","lessThan":"2092f5b38f88be306140c77aeeeb43fc1adacacc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/nfs4client.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/nfs4client.c"]}],"references":["https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913","https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3","https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89714.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89714","state":"PUBLISHED","datePublished":"2026-09-11T19:46:28.476Z","dateUpdated":"2026-10-19T08:51:27.182Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.751Z"},"containers":{"cna":{"title":"NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails\n\nnfs4_server_common_setup() allocates server->delegation_hash_table\nfirst, but server->destroy - the only path that frees the table via\nnfs4_destroy_server() - is not assigned until the very end of the\nfunction. If any intermediate step fails (the is_ds_only_client()\ncheck, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),\nthe function returns with server->destroy still NULL, so the caller's\nnfs_free_server() skips the destroy callback and the hash table is\nleaked (4 KiB per attempt with the default delegation watermark).\n\nThis is trivially reachable from userspace: every failed NFSv4 mount\nleaks one allocation. A client that persistently retries a mount that\ncannot succeed leaks kernel memory without bound. Observed in\nproduction where a Longhorn backup poller retried mount.nfs4 against\nan NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of\nunreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated\n12 GiB of leaked slab before the source was identified via the\nkmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).\n\nReproducer:\n\n  # server exports NFSv3 only (or export path absent for v4)\n  while :; do mount -t nfs4 <server>:/missing /mnt; done\n  # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration\n\nFree the table on the error paths between the allocation and the\nassignment of server->destroy."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f5b3108e6a14418b120a3c38ca589b8d6cf87627","status":"affected","lessThan":"f3adf1643517357221422c05986d6de5df7b9913","versionType":"git"},{"version":"f5b3108e6a14418b120a3c38ca589b8d6cf87627","status":"affected","lessThan":"0fd2b9687dae36be5b84eab39b4c627bb7ab33b3","versionType":"git"},{"version":"f5b3108e6a14418b120a3c38ca589b8d6cf87627","status":"affected","lessThan":"2092f5b38f88be306140c77aeeeb43fc1adacacc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/nfs4client.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/nfs4client.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913"},{"url":"https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3"},{"url":"https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:51:27.182Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}