scsi: ufs: WB is only available on LUN #0 to #7

scsi: ufs: WB is only available on LUN #0 to #7

BugLink: https://bugs.launchpad.net/bugs/1919492
[ Upstream commit a2fca52ee640a04112ed9d9a137c940ea6ad288e ]

Kernel stack violation when getting unit_descriptor/wb_buf_alloc_units from
rpmb LUN. The reason is that the unit descriptor length is different per
LU.

The length of Normal LU is 45 while the one of rpmb LU is 35.

int ufshcd_read_desc_param(struct ufs_hba *hba, ...)
{
	param_offset=41;
	param_size=4;
	buff_len=45;
	...
	buff_len=35 by rpmb LU;

	if (is_kmalloc) {
		/* Make sure we don't copy more data than available */
		if (param_offset + param_size > buff_len)
			param_size = buff_len - param_offset;
			--> param_size = 250;
		memcpy(param_read_buf, &desc_buf[param_offset], param_size);
		--> memcpy(param_read_buf, desc_buf+41, 250);

[  141.868974][ T9174] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: wb_buf_alloc_units_show+0x11c/0x11c
	}
}

Link: https://lore.kernel.org/r/20210111095927.1830311-1-jaegeuk@kernel.org
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>