{"id":"CVE-2026-89690","summary":"nfsd: defer vfree of compound ops to fix rpc_status UAF","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: defer vfree of compound ops to fix rpc_status UAF\n\nThe rpc_status netlink dumpit walks every in-flight svc_rqst under\nrcu_read_lock and, for NFSv4 requests, reads opnums out of\nargs-\u003eops[]. But args-\u003eops is a separate vmalloc buffer freed\nsynchronously by vfree() in nfsd4_release_compoundargs() at the end\nof every compound. The dumpit's rcu_read_lock pins the svc_rqst\nstruct itself (freed via kfree_rcu), but nothing defers the vfree\nof the ops buffer across the RCU grace period. A concurrent compound\ncompletion can therefore free the buffer while the dumpit is reading\nit — a use-after-free on vmalloc memory.\n\nThe trailing seqcount recheck (smp_load_acquire of rq_status_counter)\ncannot undo a load that already retired against freed memory.\n\nFix by replacing vfree(args-\u003eops) with kvfree_rcu_mightsleep(), which\ndefers the free until after an RCU grace period. This makes the\nexisting rcu_read_lock in the dumpit sufficient to protect the read.\nThe tradeoff is that completed compound ops buffers (up to\n200 * sizeof(struct nfsd4_op)) persist in memory slightly longer,\nacross one grace period, before being reclaimed.","modified":"2026-09-13T03:47:20.147957266Z","published":"2026-09-11T19:46:10.632Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89690.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/19413ccc45070a7270b9e25c2a258daf7f91de42"},{"type":"WEB","url":"https://git.kernel.org/stable/c/48f72aff24f7a7329209dc6cbc27c869f3e3595c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6703199f4d7e7f37d6a726a849eb358e8fae72fb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fca26a3fc19ed02278aa2a150af82d43db0302cb"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89690.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89690"},{"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":"bd9d6a3efa9709e653aafbeb859289feccb8e70c"},{"fixed":"48f72aff24f7a7329209dc6cbc27c869f3e3595c"},{"fixed":"6703199f4d7e7f37d6a726a849eb358e8fae72fb"},{"fixed":"19413ccc45070a7270b9e25c2a258daf7f91de42"},{"fixed":"fca26a3fc19ed02278aa2a150af82d43db0302cb"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89690.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89690.json"}}],"schema_version":"1.9.0"}