cachefiles: add consistency check for copen/cread

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: cachefiles: add consistency check for copen/cread This prevents malicious processes from completing random copen/cread requests and crashing the system. Added checks are listed below: * Generic, copen can only complete open requests, and cread can only complete read requests. * For copen, ondemand_id must not be 0, because this indicates that the request has not been read by the daemon. * For cread, the object corresponding to fd and req should be the same.

References

• https://git.kernel.org/stable/c/3b744884c0431b5a62c92900e64bfd0ed61e8e2a
• https://git.kernel.org/stable/c/36d845ccd7bf527110a65fe953886a176c209539
• https://git.kernel.org/stable/c/8aaa6c5dd2940ab934d6cd296175f43dbb32b34a
• https://git.kernel.org/stable/c/a26dc49df37e996876f50a0210039b2d211fdd6f