GHSA-CRXR-HQJJ-5W24
Vulnerability from github – Published: 2026-04-22 15:31 – Updated: 2026-04-22 15:31In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix memory leaks and NULL deref in smb2_lock()
smb2_lock() has three error handling issues after list_del() detaches smb_lock from lock_list at no_check_cl:
1) If vfs_lock_file() returns an unexpected error in the non-UNLOCK path, goto out leaks smb_lock and its flock because the out: handler only iterates lock_list and rollback_list, neither of which contains the detached smb_lock.
2) If vfs_lock_file() returns -ENOENT in the UNLOCK path, goto out leaks smb_lock and flock for the same reason. The error code returned to the dispatcher is also stale.
3) In the rollback path, smb_flock_init() can return NULL on allocation failure. The result is dereferenced unconditionally, causing a kernel NULL pointer dereference. Add a NULL check to prevent the crash and clean up the bookkeeping; the VFS lock itself cannot be rolled back without the allocation and will be released at file or connection teardown.
Fix cases 1 and 2 by hoisting the locks_free_lock()/kfree() to before the if(!rc) check in the UNLOCK branch so all exit paths share one free site, and by freeing smb_lock and flock before goto out in the non-UNLOCK branch. Propagate the correct error code in both cases. Fix case 3 by wrapping the VFS unlock in an if(rlock) guard and adding a NULL check for locks_free_lock(rlock) in the shared cleanup.
Found via call-graph analysis using sqry.
{
"affected": [],
"aliases": [
"CVE-2026-31477"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-22T14:16:44Z",
"severity": null
},
"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.",
"id": "GHSA-crxr-hqjj-5w24",
"modified": "2026-04-22T15:31:42Z",
"published": "2026-04-22T15:31:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31477"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
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