[PATCH 6.12 055/337] scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: HyeongJun An <[email protected]>

[ Upstream commit c1dea15f819cded9b3faf58f8bec72323568b6e6 ]

iscsi_tcp_hdr_dissect() receives the data segment of several PDU types
into the fixed-size conn->data buffer, which is allocated for
ISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes.  For the LOGIN_RSP, TEXT_RSP,
REJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU
whose DataSegmentLength exceeds that buffer.

The SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its
data segment (sense/response data) into conn->data via
iscsi_tcp_data_recv_prep(), but it does so without the same check.  The
only upstream bound on in.datalen is conn->max_recv_dlength, the
initiator's advertised MaxRecvDataSegmentLength, which is commonly
negotiated well above 8192 (open-iscsi defaults to 262144).  A target
that returns a SCSI Response with a DataSegmentLength between 8193 and
max_recv_dlength therefore overflows the 8192-byte conn->data buffer.

Once the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly
like those responses: bound the data segment, receive it into conn->data
when present, and otherwise complete the PDU with no data.  Fold the
opcode into that case group rather than duplicating the check.

Fixes: a081c13e39b5 ("[SCSI] iscsi_tcp: split module into lib and lld")
Suggested-by: Chris Leech <[email protected]>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: HyeongJun An <[email protected]>
Acked-by: Chris Leech <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 drivers/scsi/libiscsi_tcp.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index c182aa83f2c93..4d23205129432 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -763,13 +763,6 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 		rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
 		spin_unlock(&conn->session->back_lock);
 		break;
-	case ISCSI_OP_SCSI_CMD_RSP:
-		if (tcp_conn->in.datalen) {
-			iscsi_tcp_data_recv_prep(tcp_conn);
-			return 0;
-		}
-		rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
-		break;
 	case ISCSI_OP_R2T:
 		if (ahslen) {
 			rc = ISCSI_ERR_AHSLEN;
@@ -777,6 +770,7 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 		}
 		rc = iscsi_tcp_r2t_rsp(conn, hdr);
 		break;
+	case ISCSI_OP_SCSI_CMD_RSP:
 	case ISCSI_OP_LOGIN_RSP:
 	case ISCSI_OP_TEXT_RSP:
 	case ISCSI_OP_REJECT:
-- 
2.53.0