CVE-2026-64192bpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is uninitialized

Official description

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is uninitialized When CONFIG_BPF_LSM=y is set, BPF inode storage maps (BPF_MAP_TYPE_INODE_STORAGE) are compiled into the kernel. However, if the BPF LSM is not explicitly enabled at boot time (e.g. omitted from the "lsm=" boot parameter), lsm_prepare() is never executed for the BPF LSM. Consequently, the BPF inode security blob offset (bpf_lsm_blob_sizes.lbs_inode) is never initialized and remains at its default compiled size of 8 bytes instead of being updated to a valid offset past the reserved struct rcu_head (typically 16 bytes or more). When a privileged user creates and updates a BPF_MAP_TYPE_INODE_STORAGE map, bpf_inode() evaluates inode->i_security + 8. This erroneously aliases the struct rcu_head.func callback pointer at the beginning of the inode->i_security blob. During subsequent map element cleanup or inode destruction, writing NULL to owner_storage clears the queued RCU callback pointer. When rcu_do_batch() later executes the queued callback, it attempts an instruction fetch at address 0x0, triggering an immediate kernel panic. Fix this by introducing a global bpf_lsm_initialized boolean flag marked with __ro_after_init. Set this flag to true inside bpf_lsm_init() when the LSM framework successfully registers the BPF LSM. Gate map allocation in inode_storage_map_alloc() on this flag, returning -EOPNOTSUPP if the BPF LSM is in turn uninitialized. This fail-fast approach prevents userspace from allocating inode storage maps when the supporting BPF LSM infrastructure is absent, avoiding zombie map states.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/413b14b9623a2e6ee131c2b2152b304aeb04e378
• https://git.kernel.org/stable/c/a6d634f794c808a261eac7d5af023a7e06b9ecd8
• https://git.kernel.org/stable/c/721f669853bdbf46b475a81bb5d05d610f8c19de
• https://git.kernel.org/stable/c/5337eebdf8c5d4810b1913047f078d2815d5645f
• https://git.kernel.org/stable/c/de984ea883405420fdc416ae8964b752df586970
• https://git.kernel.org/stable/c/267fdd9b6530c399dfd996e1a0a7628b45baf9f0
• https://git.kernel.org/stable/c/c76b8abce575e0c6e4096957220b4515ed847d89
• https://git.kernel.org/stable/c/a6f0643e4f63cfaa0d5d4a69de4f132eac4b8fe4