The Linux kernel contained a vulnerability where the bdev pseudo-filesystem, an internal kernel filesystem, could be mounted by userspace. This is problematic because the system call move_mount() uses pointers from the inode_operations structure, which for the bdev pseudo-filesystem are always zero (empty_iops). Attempting to access files on this filesystem leads to a NULL pointer dereference in kernel space, causing a kernel crash. The vulnerability was discovered by the Linux Verification Center using Syzkaller. The fix involves unregistering the bdev pseudo-filesystem so that userspace cannot mount it, eliminating the NULL pointer dereference condition.

Exploitation of this vulnerability causes a kernel NULL pointer dereference, resulting in a kernel crash (oops). This affects system stability and could lead to denial of service. There is no indication of privilege escalation or code execution from the provided data.

A fix has been implemented in the Linux kernel to unregister the bdev pseudo-filesystem, preventing userspace from mounting it and thus avoiding the NULL pointer dereference. Users should update their Linux kernel to a version that includes this fix. Patch status is not explicitly stated in the provided data; therefore, check the vendor advisory or Linux kernel release notes for the exact fixed version and update accordingly.