CVE-2026-98775nitro_enclaves: fix use-after-free on SLOT_ALLOC failure

Official description

In the Linux kernel, the following vulnerability has been resolved: nitro_enclaves: fix use-after-free on SLOT_ALLOC failure When ne_create_vm_ioctl() fails the SLOT_ALLOC request after anon_inode_getfile() has succeeded, the error path calls fput(enclave_file) and then frees ne_enclave. In normal userspace context, fput() defers the final __fput() via task_work. ne_enclave_release() therefore runs after ne_enclave has already been freed and dereferences ne_enclave->slot_uid, causing a use-after-free: KASAN: slab-use-after-free in ne_enclave_release. The enclave has no slot allocated and is not yet linked into the enclaves list on this error path, so ne_enclave_release() is expected to return early when slot_uid is zero. However, reading slot_uid already accesses the freed object. Clear enclave_file->private_data before fput() on the error path. ne_enclave_release() then returns immediately when private_data is NULL, leaving the ioctl error path as the sole owner of ne_enclave. This is safe because the file has not been fd_install()'d yet. Tested on an AWS EC2 m5.2xlarge with CONFIG_KASAN=y. Without the patch, the reproducer triggers a KASAN slab-use-after-free on every SLOT_ALLOC failure. With the patch, no KASAN report is produced and the SLOT_ALLOC error is still returned. Normal enclave creation and teardown are unaffected.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/718965a5fcea47f7ec6accff55306317aadc3af3
• https://git.kernel.org/stable/c/dac89ed976d9826eae4703281d0d51b062b58eef
• https://git.kernel.org/stable/c/8024c50b8763add7912b6d9830327ba73f994204
• https://git.kernel.org/stable/c/8bde6f643ab6fe5e3e3f4c312f84ce327ecf39b2
• https://git.kernel.org/stable/c/466041d14f26dc2babd606a2e85dce08774112a6
• https://git.kernel.org/stable/c/f7fb6c2835ede1b8ad84cf7e78a528a9d0159b84
• https://git.kernel.org/stable/c/43f78b328f3907ca2f7424e15b7e45ffbf9fe21c
• https://git.kernel.org/stable/c/9bc184a2eda8b773c88ecbff934001ad649b9cc1