CVE-2026-98687: thunderbolt: Reject oversized XDomain properties responses

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

thunderbolt: Reject oversized XDomain properties responses

tbxdppropertiesrequest() allocates room for 45 data dwords in its 252-byte response buffer. The XDomain length field is six bits wide, however, and a malicious peer can set it to 63. After the fixed response fields are subtracted, the driver treats this as 48 data dwords.

Commit 322e93448d90 ("thunderbolt: Clamp XDomain response data copy to allocation size") only bounds the copy against datalen. If datalen is at least 48, memcpy() reads 192 bytes from the 180-byte res->data array, causing a 12-byte heap out-of-bounds read. Commit 4db2bd2ed478 ("thunderbolt: Limit XDomain response copy to actual frame size") limits the earlier copy but does not constrain this header-derived length.

Reject response data lengths that exceed the allocated source buffer before copying them into the assembled property block.