{"id":"CVE-2026-31477","summary":"ksmbd: fix memory leaks and NULL deref in smb2_lock()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix memory leaks and NULL deref in smb2_lock()\n\nsmb2_lock() has three error handling issues after list_del() detaches\nsmb_lock from lock_list at no_check_cl:\n\n1) If vfs_lock_file() returns an unexpected error in the non-UNLOCK\n   path, goto out leaks smb_lock and its flock because the out:\n   handler only iterates lock_list and rollback_list, neither of\n   which contains the detached smb_lock.\n\n2) If vfs_lock_file() returns -ENOENT in the UNLOCK path, goto out\n   leaks smb_lock and flock for the same reason.  The error code\n   returned to the dispatcher is also stale.\n\n3) In the rollback path, smb_flock_init() can return NULL on\n   allocation failure.  The result is dereferenced unconditionally,\n   causing a kernel NULL pointer dereference.  Add a NULL check to\n   prevent the crash and clean up the bookkeeping; the VFS lock\n   itself cannot be rolled back without the allocation and will be\n   released at file or connection teardown.\n\nFix cases 1 and 2 by hoisting the locks_free_lock()/kfree() to before\nthe if(!rc) check in the UNLOCK branch so all exit paths share one\nfree site, and by freeing smb_lock and flock before goto out in the\nnon-UNLOCK branch.  Propagate the correct error code in both cases.\nFix case 3 by wrapping the VFS unlock in an if(rlock) guard and adding\na NULL check for locks_free_lock(rlock) in the shared cleanup.\n\nFound via call-graph analysis using sqry.","modified":"2026-07-08T06:28:15.989753834Z","published":"2026-04-22T13:54:05.470Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31477.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/309b44ed684496ed3f9c5715d10b899338623512"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3cdacd11b41569ce75b3162142240f2355e04900"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91aeaa7256006d79a37298f5a1df23325db91599"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aab42f0795620cf0d3955a520f571f697d0f9a2a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cdac6f7e7e428dc70e3b5898ac6999a72ed13993"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31477.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31477"},{"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":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9"},{"fixed":"cdac6f7e7e428dc70e3b5898ac6999a72ed13993"},{"fixed":"c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9"},{"fixed":"91aeaa7256006d79a37298f5a1df23325db91599"},{"fixed":"3cdacd11b41569ce75b3162142240f2355e04900"},{"fixed":"aab42f0795620cf0d3955a520f571f697d0f9a2a"},{"fixed":"309b44ed684496ed3f9c5715d10b899338623512"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31477.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.15.0"},{"fixed":"6.1.168"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.131"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31477.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:N/I:N/A:H"}]}