scsi: qla2xxx: Validate BSG request_len before reading vendor_cmd[]

In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: Validate BSG request_len before reading vendor_cmd[] The FC BSG transport allocates job->request via memdup_user() using the exact user-supplied request_len. For FC_BSG_HST_VENDOR, fc_bsg_host_dispatch() only guarantees request_len covers msgcode and vendor_id; it does not account for the vendor_cmd[] flexible array. qla2xxx then reads the command selector vendor_cmd[0] and, in several sub-handlers, vendor_cmd[1]/[2] or structures overlaid on the vendor command area without verifying request_len. A caller holding CAP_SYS_RAWIO can submit a short request whose vendor_id matches the host, triggering out-of-bounds heap reads (KASAN-detectable, and able to mis-select a command or panic). Add a central guard in qla2x00_process_vendor_specific() so the selector is always in bounds, restrict the early vendor_cmd[0] read in qla24xx_bsg_request() to sufficiently long vendor messages, and add request_len checks to the sub-handlers that read further: qla24xx_proc_fcp_prio_cfg_cmd(), qla2x00_process_loopback(), qla84xx_reset(), qla84xx_updatefw(), qla2x00_read_optrom(), qla2x00_update_optrom(), qlafx00_mgmt_cmd() and qla28xx_validate_flash_image().