CVE-2026-68083ksmbd: fix path resolution in ksmbd_vfs_kern_path_create

Official description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix path resolution in ksmbd_vfs_kern_path_create The SMB2 open lookup is rooted at the share with LOOKUP_BENEATH, but the create/mkdir/hardlink sink is not: ksmbd_vfs_kern_path_create() builds an absolute path with convert_to_unix_name() and resolves it from AT_FDCWD via start_creating_path(), so a ".." component is walked from the real filesystem root and escapes the export. An authenticated client races a missing path component so the rooted open lookup returns -ENOENT (taking the create branch) while the same component is present (a directory) when the create walk runs; the create then resolves ".." out of the share. Root the create walk at the share like the lookup and rename paths already are: resolve the parent with vfs_path_parent_lookup(..., LOOKUP_BENEATH, &share_conf->vfs_path) and create the final component with start_creating_noperm(). convert_to_unix_name() then has no callers and is removed.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/f1f53dc95edfb3d2072e5e8cd8eb9a2fe7d7f2d0
• https://git.kernel.org/stable/c/a2516be69048856e2a49a51e00975dc59431f95c
• https://git.kernel.org/stable/c/489d1ded01425c0fb33418172c0e4e588467526b
• https://git.kernel.org/stable/c/c7c884a1305aa4540eb7942a50bd356b34120e1f
• https://git.kernel.org/stable/c/98185b3025beeae92d1fe700d5db26b9ac4bf025
• https://git.kernel.org/stable/c/1c8951963d8ed357f70f59e0ad4ddce2199d2016