[PATCH v2] scsi: ufs: WB is not allowed in RPMB_LUN

[Jaegeuk Kim <jaegeuk@kernel.org>]

From: Jaegeuk Kim <jaegeuk@google.com>

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

The lengh 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
	}
}

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 drivers/scsi/ufs/ufs-sysfs.c | 3 ++-
 drivers/scsi/ufs/ufs.h       | 6 ++++--
 drivers/scsi/ufs/ufshcd.c    | 2 +-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
index 08e72b7eef6a..50e90416262b 100644
--- a/drivers/scsi/ufs/ufs-sysfs.c
+++ b/drivers/scsi/ufs/ufs-sysfs.c
@@ -792,7 +792,8 @@ static ssize_t _pname##_show(struct device *dev,			\
 	struct scsi_device *sdev = to_scsi_device(dev);			\
 	struct ufs_hba *hba = shost_priv(sdev->host);			\
 	u8 lun = ufshcd_scsi_to_upiu_lun(sdev->lun);			\
-	if (!ufs_is_valid_unit_desc_lun(&hba->dev_info, lun))		\
+	if (!ufs_is_valid_unit_desc_lun(&hba->dev_info, lun,		\
+				_duname##_DESC_PARAM##_puname))		\
 		return -EINVAL;						\
 	return ufs_sysfs_read_desc_param(hba, QUERY_DESC_IDN_##_duname,	\
 		lun, _duname##_DESC_PARAM##_puname, buf, _size);	\
diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index 14dfda735adf..7a0069c83900 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -552,13 +552,15 @@ struct ufs_dev_info {
  * @return: true if the lun has a matching unit descriptor, false otherwise
  */
 static inline bool ufs_is_valid_unit_desc_lun(struct ufs_dev_info *dev_info,
-		u8 lun)
+		u8 lun, u8 param_offset)
 {
 	if (!dev_info || !dev_info->max_lu_supported) {
 		pr_err("Max General LU supported by UFS isn't initialized\n");
 		return false;
 	}
-
+	/* WB is not allowed in RPMB_WLUN */
+	if (param_offset == UNIT_DESC_PARAM_WB_BUF_ALLOC_UNITS)
+		return lun < dev_info->max_lu_supported;
 	return lun == UFS_UPIU_RPMB_WLUN || (lun < dev_info->max_lu_supported);
 }
 
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 2a715f13fe1d..48cbd4f294dd 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -3425,7 +3425,7 @@ static inline int ufshcd_read_unit_desc_param(struct ufs_hba *hba,
 	 * Unit descriptors are only available for general purpose LUs (LUN id
 	 * from 0 to 7) and RPMB Well known LU.
 	 */
-	if (!ufs_is_valid_unit_desc_lun(&hba->dev_info, lun))
+	if (!ufs_is_valid_unit_desc_lun(&hba->dev_info, lun, param_offset))
 		return -EOPNOTSUPP;
 
 	return ufshcd_read_desc_param(hba, QUERY_DESC_IDN_UNIT, lun,
-- 
2.30.0.284.gd98b1dd5eaa7-goog