Linux Kernel CVE-2026-80546

In the Linux kernel, the following vulnerability has been resolved:

s390/zcrypt: Improve CCA CPRB length and overflow checks

The xcrb_msg_to_type6cprb_msgx() function lacks proper input validation, creating security vulnerabilities:

1. Integer overflow after CEIL4 alignment: Signed int variables could

overflow during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking.

1. Missing minimum size validation: The CPRBX structure is copied from

userspace without verifying sufficient buffer length. Undersized buffers cause uninitialized memory access when reading structure fields like cprbx.cprb_len and cprbx.domain.

1. Arithmetic overflow in sum calculations: Adding control block and

data block sizes could overflow, bypassing size checks and enabling buffer overflows.

Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, validating minimum control block size before copying from userspace, and detecting sum calculation overflows.