[PATCH] scsi: libiscsi: fix stale-data leak into the SCSI sense buffer

[HyeongJun An]

iscsi_scsi_cmd_rsp() copies the sense data of a SCSI Response from the
target-supplied data segment.  The segment carries a 2-byte sense length
followed by the sense bytes, so it must hold 2 + senselen bytes, but the
bounds check only requires datalen >= senselen:

	senselen = get_unaligned_be16(data);
	if (datalen < senselen)
		goto invalid_datalen;
	memcpy(sc->sense_buffer, data + 2,
	       min_t(uint16_t, senselen, SCSI_SENSE_BUFFERSIZE));

A target that returns a SCSI Response whose datalen equals senselen (with
senselen <= SCSI_SENSE_BUFFERSIZE) makes the memcpy() from data + 2 read
up to two bytes past the received data.  Those bytes are stale conn->data
contents and end up in the command's sense buffer, which is returned to
userspace.

Account for the 2-byte sense length prefix in the check.

Fixes: 7996a778ff8c ("[SCSI] iscsi: add libiscsi")
Suggested-by: Sashiko AI <sashiko-bot@xxxxxxxxxx>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: HyeongJun An <sammiee5311@xxxxxxxxx>
---
 drivers/scsi/libiscsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 160f02f2f51d..5cbc51899de0 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -918,7 +918,7 @@ static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		}
 
 		senselen = get_unaligned_be16(data);
-		if (datalen < senselen)
+		if (datalen < senselen + 2)
 			goto invalid_datalen;
 
 		memcpy(sc->sense_buffer, data + 2,
-- 
2.43.0