From: Yuxiao Wang 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. Fixes: 9c8eb50fe9e2 ("nitro_enclaves: Add logic for terminating an enclave") Cc: stable@vger.kernel.org Co-developed-by: Zhaofeng Chen Signed-off-by: Zhaofeng Chen Signed-off-by: Yuxiao Wang Reviewed-by: Alexander Graf --- drivers/virt/nitro_enclaves/ne_misc_dev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c b/drivers/virt/nitro_enclaves/ne_misc_dev.c index c91300a..0d7bdad 100644 --- a/drivers/virt/nitro_enclaves/ne_misc_dev.c +++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c @@ -1706,6 +1706,7 @@ static int ne_create_vm_ioctl(struct ne_pci_dev *ne_pci_dev, u64 __user *slot_ui return enclave_fd; put_file: + enclave_file->private_data = NULL; fput(enclave_file); put_fd: put_unused_fd(enclave_fd); -- 2.34.1