CVE-2020-10690: Use After Free

There is a use-after-free in kernel versions before 5.5 due to a race condition between the release of ptpclock and cdev while resource deallocation. When a (high privileged) process allocates a ptp device file (like /dev/ptpX) and voluntarily goes to sleep. During this time if the underlying device is removed, it can cause an exploitable condition as the process wakes up to terminate and clean all attached files. The system crashes due to the cdev structure being invalid (as already freed) which is pointed to by the inode.

There is a use-after-free problem seen due to a race condition between the release of ptpclock and cdev while resource deallocation. When a (high privileged) process allocates a ptp device file (like /dev/ptpX) and voluntarily goes to sleep. During this time if the underlying device is removed, it can cause an exploitable condition as the process wakes up to terminate and clean all attached files. The system crashes due to the cdev structure being invalid (as already freed) which is pointed to by the inode.

There was a use-after-free problem seen due to a race condition between the release of ptpclock and cdev at the time of resource deallocation.

When a (high privileged) process allocates a ptp device file (like /dev/ptpX) and voluntarily goes to sleep. During this time if the underlying device is removed (a potential privilege escalation) by the user with administrator privilege, it can cause a denial of service (DoS) problem as the process wakes up to terminate and cleanup all attached files/resources.

The system crashes due to the cdev structure being invalid (as already freed) which is pointed to by the inode.

Refer: https://lore.kernel.org/linux-fsdevel/20191125125342.6189-1-vdronov@redhat.com/T/#u

— Red Hat