[PATCH v2] scsi: stex: properly zero out the passthrough command structure

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Linus Torvalds <torvalds@linux-foundation.org>

The passthrough structure is declared off of the stack, so it needs to
be set to zero before copied back to userspace to prevent any
unintentional data leakage.  Switch things to be statically allocated
which will fill the unused fields with 0 automatically.

Reported-by: hdthky <hdthky0@gmail.com>
Cc: stable <stable@kernel.org>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 v2: Linus's updated version that moves the initialization to be
     statically defined and changes the function prototype and structure
     to be const.

 drivers/scsi/stex.c      | 17 +++++++++--------
 include/scsi/scsi_cmnd.h |  2 +-
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/stex.c b/drivers/scsi/stex.c
index e6420f2127ce..8def242675ef 100644
--- a/drivers/scsi/stex.c
+++ b/drivers/scsi/stex.c
@@ -665,16 +665,17 @@ static int stex_queuecommand_lck(struct scsi_cmnd *cmd)
 		return 0;
 	case PASSTHRU_CMD:
 		if (cmd->cmnd[1] == PASSTHRU_GET_DRVVER) {
-			struct st_drvver ver;
+			const struct st_drvver ver = {
+				.major = ST_VER_MAJOR,
+				.minor = ST_VER_MINOR,
+				.oem = ST_OEM,
+				.build = ST_BUILD_VER,
+				.signature[0] = PASSTHRU_SIGNATURE,
+				.console_id = host->max_id - 1,
+				.host_no = hba->host->host_no,
+			};
 			size_t cp_len = sizeof(ver);
 
-			ver.major = ST_VER_MAJOR;
-			ver.minor = ST_VER_MINOR;
-			ver.oem = ST_OEM;
-			ver.build = ST_BUILD_VER;
-			ver.signature[0] = PASSTHRU_SIGNATURE;
-			ver.console_id = host->max_id - 1;
-			ver.host_no = hba->host->host_no;
 			cp_len = scsi_sg_copy_from_buffer(cmd, &ver, cp_len);
 			if (sizeof(ver) == cp_len)
 				cmd->result = DID_OK << 16;
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index bac55decf900..7d3622db38ed 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -201,7 +201,7 @@ static inline unsigned int scsi_get_resid(struct scsi_cmnd *cmd)
 	for_each_sg(scsi_sglist(cmd), sg, nseg, __i)
 
 static inline int scsi_sg_copy_from_buffer(struct scsi_cmnd *cmd,
-					   void *buf, int buflen)
+					   const void *buf, int buflen)
 {
 	return sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd),
 				   buf, buflen);
-- 
2.37.3