scsi: qla2xxx: Sanitize payload size to prevent member overflow

scsi: qla2xxx: Sanitize payload size to prevent member overflow

In qla27xx_copy_fpin_pkt() and qla27xx_copy_multiple_pkt(), the frame_size
reported by firmware is used to calculate the copy length into
item->iocb. However, the iocb member is defined as a fixed-size 64-byte
array within struct purex_item.

If the reported frame_size exceeds 64 bytes, subsequent memcpy calls will
overflow the iocb member boundary. While extra memory might be allocated,
this cross-member write is unsafe and triggers warnings under
CONFIG_FORTIFY_SOURCE.

Fix this by capping total_bytes to the size of the iocb member (64 bytes)
before allocation and copying. This ensures all copies remain within the
bounds of the destination structure member.

Fixes: 875386b98857 ("scsi: qla2xxx: Add Unsolicited LS Request and Response Support for NVMe")
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Reviewed-by: Himanshu Madhani <hmadhani2024@gmail.com>
Link: https://patch.msgid.link/20260106205344.18031-1-jiashengjiangcool@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>