CVE-2026-46057landlock: Fix LOG_SUBDOMAINS_OFF inheritance across fork()

Official description

In the Linux kernel, the following vulnerability has been resolved: landlock: Fix LOG_SUBDOMAINS_OFF inheritance across fork() hook_cred_transfer() only copies the Landlock security blob when the source credential has a domain. This is inconsistent with landlock_restrict_self() which can set LOG_SUBDOMAINS_OFF on a credential without creating a domain (via the ruleset_fd=-1 path): the field is committed but not preserved across fork() because the child's prepare_creds() calls hook_cred_transfer() which skips the copy when domain is NULL. This breaks the documented use case where a process mutes subdomain logs before forking sandboxed children: the children lose the muting and their domains produce unexpected audit records. Fix this by unconditionally copying the Landlock credential blob.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/2fcde49092aac55d5beef43fdd3633217672f7d1
• https://git.kernel.org/stable/c/1c513b8a00df13d231021e74ad92babb3fedf64a
• https://git.kernel.org/stable/c/874c8f83826c95c62c21d9edfe9ef43e5c346724