Linux Kernel Acct System Call NULL Dereference Vulnerability

A vulnerability in the Linux kernel's acct system call can lead to a NULL dereference. This issue occurs when the acct system call is directed to write to a file that requires an internal lookup, such as /sys/power/resume. When the write operation is performed, the calling task has already exited and released its file system resources, causing the lookup to dereference a NULL pointer. The vulnerability has been addressed by modifying the code to perform the final write from a workqueue using the caller's credentials, thereby maintaining the existing permission model with minimal risk of regression.

Impact

Exploitation of this vulnerability causes a NULL pointer dereference, which can lead to a system crash or undefined behavior.