CVE-2026-89751

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

x86/tdx: Fix off-by-one in port I/O handling

handle in() and handle out() in arch/x86/coco/tdx/tdx.c use:

u64 mask = GENMASK(BITS PER BYTE * size, 0);

GENMASK(h, l) includes bit h. For size=1 (INB), this produces GENMASK(8, 0) = 0x1FF (9 bits) instead of GENMASK(7, 0) = 0xFF (8 bits). The mask is one bit too wide for all I/O sizes.

Fix the mask calculation.