Linux Kernel bdev Pseudo-Filesystem Mounting Vulnerability

A vulnerability in the Linux kernel's handling of the bdev pseudo-filesystem has been addressed. This internal filesystem should not be accessed by userspace. The vulnerability arose because the system call move_mount() relied on pointers in the inode_operations structure that were always null for the bdev pseudo-filesystem. This led to a kernel NULL pointer dereference error when files were accessed, causing a crash. The issue has been fixed by unregistering the bdev filesystem, preventing userspace from attempting to mount it.

Impact

Exploitation of this vulnerability could lead to a kernel NULL pointer dereference, causing a system crash.

Reproduction

The vulnerability can be reproduced by attempting to access files through the bdev pseudo-filesystem while it is registered and available for mounting in userspace. This can be done using the move_mount() system call, which will trigger the NULL pointer dereference error.

Remediation

Users can upgrade to the patched version of the Linux kernel where this vulnerability has been addressed.