s390/zcrypt: Improve CCA CPRB length and overflow checks

Summary

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. 2. 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. 3. 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.

Timeline

1. Aug 26, 2026, 2:37 PM UTCCVE published
2. Oct 21, 2026, 12:46 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 20b0b0159390fa5c00a435195649680fefda81e0 · fixed in 584400144020f40365de3972c4763da520e7280e; From e2c6d91eb8b1533753755f07803e47eceed263d0 · fixed in 50fe5133dcb46449daf2435fa705264364411129; From e2c6d91eb8b1533753755f07803e47eceed263d0 · fixed in 35ac6754ba6da45fd193f5ce3f665f7490b830d5; From 6.12.114 · fixed in 6.13

• Linux Linux

  7.1

• KernelLinux

  From 7.1.0 · fixed in 7.1.10

References 3