CVE-2026-89969
Description
In the Linux kernel, the following vulnerability has been resolved:
nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU
nvmet_tcp_try_recv_pdu() reads a PDU header into the fixed 128-byte
queue->pdu union, then computes the remaining payload length as
queue->left = hdr->hlen - queue->offset + hdgst;
and reads that many more bytes into &queue->pdu + queue->offset, without
ever bounding the result against sizeof(queue->pdu).
A struct nvme_tcp_icreq_pdu is itself 128 bytes, exactly the size of the
union. Once a header digest has been negotiated (hdgst = 4), a second
ICReq passes the hlen == nvmet_tcp_pdu_size() check but yields
queue->left = 128 - 8 + 4 = 124, so bytes 8..132 are written into the
128-byte buffer -- 4 bytes past its end, over queue->hdr_digest and
queue->data_digest. Those bytes are attacker-controlled (an ICReq
carries no digest), and the duplicate ICReq is only rejected later,
after the overflow. A remote unauthenticated host can thus corrupt
kernel memory adjacent to the receive buffer.
Reject any PDU whose declared length would read past the end of
queue->pdu before the second recv.