CVE-2026-80545s390/zcrypt: Improve EP11 CPRB length and overflow checks

Official description

In the Linux kernel, the following vulnerability has been resolved: s390/zcrypt: Improve EP11 CPRB length and overflow checks The xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Missing minimum size validation: The ep11_cprb structure and subsequent payload fields (pld_tag, pld_lenfmt) are copied from userspace without verifying sufficient buffer length. 2. Arithmetic overflow in length calculations: CEIL4 alignment could overflow, bypassing size checks and enabling buffer overflows. 3. The payload is asn1 encoded but the function just uses a simple c struct overlay to access some fields of the payload. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, and validating minimum request size and minimum reply size before copying from userspace. Do a very simple asn1 parsing of the payload up to the function value field.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/f463f474773aa49ed1d6087d95d44cea7099fdc7
• https://git.kernel.org/stable/c/2976b9d2e716c7e5487ca7c29a7bd076cf9adf08
• https://git.kernel.org/stable/c/17ac0bc866fc624cd05f022dcd8b730c0af11bb1