CVE-2026-89969

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

nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU

nvmettcptryrecvpdu() 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 nvmetcpicreq_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 == nvmettcppdu_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.