CVE-2026-89571

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

cxl/features: bound fwctl command payload to the input buffer

fwctl_cmd_rpc() copies cmd->in_len bytes into inbuf = kvzalloc(cmd->in_len)

and passes inbuf and in_len to ->fw_rpc(). The CXL callback cxlctl_fw_rpc()

ignores in_len and never checks the user-controlled op_size against it.

cxlctl_set_feature() bounds op_size only from below

(op_size <= sizeof(feat_in->hdr)) and then reads op_size - sizeof(hdr)

bytes from feat_in->feat_data via cxl_set_feature(). With a small in_len

and a large op_size the first memcpy() already reads past the

kvzalloc(in_len) buffer; the out-of-bounds bytes are placed in the mailbox

payload and sent to the device, and a large enough op_size can walk into

unmapped memory and oops the kernel. The Get paths pin op_size to a fixed

size but likewise read the input struct without checking in_len.

Reject, at the single dispatch point, any request whose fixed header plus

op_size does not fit in the copied-in buffer. The lower-bound test guards

the subtraction and ensures op_size was copied in before it is read.