Null Pointer Dereference Vulnerability in Linux Kernel's Fanotify Functionality

CVE-2025-40072

What is CVE-2025-40072?

The Linux Kernel contains a vulnerability in the fanotify subsystem where the function do_fanotify_mark() fails to validate the return value of mnt_ns_from_dentry() before accessing the dereferenced pointer. This oversight can lead to a NULL pointer dereference, triggering a crash when a non-mount namespace object is processed. The vulnerability has been addressed by implementing a check for the return value of mnt_ns_from_dentry() prior to dereferencing, thus improving the robustness of the fanotify operations and preventing unexpected kernel panics.

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