FKIE_CVE-2026-31477

Vulnerability from fkie_nvd - Published: 2026-04-22 14:16 - Updated: 2026-04-23 16:17
Severity ?
Summary
In 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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/309b44ed684496ed3f9c5715d10b899338623512
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3cdacd11b41569ce75b3162142240f2355e04900
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/91aeaa7256006d79a37298f5a1df23325db91599
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/aab42f0795620cf0d3955a520f571f697d0f9a2a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cdac6f7e7e428dc70e3b5898ac6999a72ed13993
Impacted products
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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": "CVE-2026-31477",
  "lastModified": "2026-04-23T16:17:41.280",
  "metrics": {},
  "published": "2026-04-22T14:16:44.440",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/309b44ed684496ed3f9c5715d10b899338623512"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3cdacd11b41569ce75b3162142240f2355e04900"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/91aeaa7256006d79a37298f5a1df23325db91599"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/aab42f0795620cf0d3955a520f571f697d0f9a2a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cdac6f7e7e428dc70e3b5898ac6999a72ed13993"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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