CVE-2026-43495: net: wwan: t7xx: validate port_count against message length in t7xx_port_enum_msg_handler

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

net: wwan: t7xx: validate portcount against message length in t7xxportenummsghandler

t7xxportenummsghandler() uses the modem-supplied portcount field as a loop bound over portmsg->data[] without checking that the message buffer contains sufficient data. A modem sending portcount=65535 in a 12-byte buffer triggers a slab-out-of-bounds read of up to 262140 bytes.

Add a sizeof(portmsg) check before accessing the port message header fields to guard against undersized messages.

Add a structsize() check after extracting portcount and before the loop.

In t7xxparsehostrtdata(), guard the rtfeature header read with a remaining-buffer check before accessing datalen, validate featdatalen against the actual remaining buffer to prevent OOB reads and signed integer overflow on offset.

Pass msglen from both call sites: skb->len at the DPMAIF path after skbpull(), and the validated featdatalen at the handshake path.