{"id":"CVE-2026-31444","summary":"ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free and NULL deref in smb_grant_oplock()\n\nsmb_grant_oplock() has two issues in the oplock publication sequence:\n\n1) opinfo is linked into ci-\u003em_op_list (via opinfo_add) before\n   add_lease_global_list() is called.  If add_lease_global_list()\n   fails (kmalloc returns NULL), the error path frees the opinfo\n   via __free_opinfo() while it is still linked in ci-\u003em_op_list.\n   Concurrent m_op_list readers (opinfo_get_list, or direct iteration\n   in smb_break_all_levII_oplock) dereference the freed node.\n\n2) opinfo-\u003eo_fp is assigned after add_lease_global_list() publishes\n   the opinfo on the global lease list.  A concurrent\n   find_same_lease_key() can walk the lease list and dereference\n   opinfo-\u003eo_fp-\u003ef_ci while o_fp is still NULL.\n\nFix by restructuring the publication sequence to eliminate post-publish\nfailure:\n\n- Set opinfo-\u003eo_fp before any list publication (fixes NULL deref).\n- Preallocate lease_table via alloc_lease_table() before opinfo_add()\n  so add_lease_global_list() becomes infallible after publication.\n- Keep the original m_op_list publication order (opinfo_add before\n  lease list) so concurrent opens via same_client_has_lease() and\n  opinfo_get_list() still see the in-flight grant.\n- Use opinfo_put() instead of __free_opinfo() on err_out so that\n  the RCU-deferred free path is used.\n\nThis also requires splitting add_lease_global_list() to take a\npreallocated lease_table and changing its return type from int to void,\nsince it can no longer fail.","modified":"2026-06-18T03:56:23.315707136Z","published":"2026-04-22T13:53:41.351Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31444.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/48623ec358c1c600fa1e38368746f933e0f1a617"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6d7e5a918c1d0aad06db0e17677b66fc9a471021"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7de55bba69cbf0f9280daaea385daf08bc076121"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9e785f004cbc56390479b77375726ea9b0d1a8a6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a5c6f6d6ceefed2d5210ee420fb75f8362461f46"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31444.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31444"},{"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":"302fef75512b2c8329a3f5efab1ae7ba2562387a"},{"fixed":"9e785f004cbc56390479b77375726ea9b0d1a8a6"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c"},{"fixed":"7de55bba69cbf0f9280daaea385daf08bc076121"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1d6abf145615dbfe267ce3b0a271f95e3780e18e"},{"fixed":"a5c6f6d6ceefed2d5210ee420fb75f8362461f46"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ce8507ee82c888126d8e7565e27c016308d24cde"},{"fixed":"6d7e5a918c1d0aad06db0e17677b66fc9a471021"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1dfd062caa165ec9d7ee0823087930f3ab8a6294"},{"fixed":"48623ec358c1c600fa1e38368746f933e0f1a617"}]}],"versions":["v6.6.130","v6.12.79","v6.12.78","v6.18.20","v6.18.19","v6.19.10","v6.19.9"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31444.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.6.130"},{"fixed":"6.6.131"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.12.78"},{"fixed":"6.12.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.18.19"},{"fixed":"6.18.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.9"},{"fixed":"6.19.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-31444.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}