CVE-2022-49873 Information

Description

In the Linux kernel the following vulnerability has been resolved:

bpf: Fix wrong reg type conversion in release_reference()

Some helper functions will allocate memory. To avoid memory leaks the verifier requires the eBPF program to release these memories by calling the corresponding helper functions.

When a resource is released all pointer registers corresponding to the resource should be invalidated. The verifier use release_references() to do this job by apply __mark_reg_unknown() to each relevant register.

It will give these registers the type of SCALAR_VALUE. A register that will contain a pointer value at runtime but of type SCALAR_VALUE which may allow the unprivileged user to get a kernel pointer by storing this register into a map.

Using __mark_reg_not_init() while NOT allow_ptr_leaks can mitigate this problem.

Reference

https://git.kernel.org/stable/c/466ce46f251dfb259a8cbaa895ab9edd6fb56240 https://git.kernel.org/stable/c/ae5ccad6c711db0f2ca1231be051935dd128b8f5 https://git.kernel.org/stable/c/cedd4f01f67be94735f15123158f485028571037 https://git.kernel.org/stable/c/f1db20814af532f85e091231223e5e4818e8464b