[PATCH] scsi: ips: Avoid over-read of sense buffer

[PATCH] scsi: ips: Avoid over-read of sense buffer

[Kees Cook]

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy() avoid intentionally reading across
neighboring array fields.

scb->scsi_cmd->sense_buffer is 96 bytes:
	#define SCSI_SENSE_BUFFERSIZE        96

tapeDCDB->sense_info is 56 bytes:
	typedef struct {
	   ...
	   uint8_t   sense_info[56];
	} IPS_DCDB_TABLE_TAPE, ...

scb->dcdb.sense_info is 64 bytes:
	typedef struct {
	   ...
	   uint8_t   sense_info[64];
	   ...
	} IPS_DCDB_TABLE, ...

Copying 96 bytes from either was copying beyond the end of the respective
buffers, leading to potential memory content exposures. Correctly copy
the actual buffer contents and zero pad the remaining bytes.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/scsi/ips.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/ips.c b/drivers/scsi/ips.c
index bc33d54a4011..8b33c9871484 100644
--- a/drivers/scsi/ips.c
+++ b/drivers/scsi/ips.c
@@ -3344,13 +3344,15 @@ ips_map_status(ips_ha_t * ha, ips_scb_t * scb, ips_stat_t * sp)
 					IPS_CMD_EXTENDED_DCDB_SG)) {
 					tapeDCDB =
 					    (IPS_DCDB_TABLE_TAPE *) & scb->dcdb;
-					memcpy(scb->scsi_cmd->sense_buffer,
+					memcpy_and_pad(scb->scsi_cmd->sense_buffer,
+					       SCSI_SENSE_BUFFERSIZE,
 					       tapeDCDB->sense_info,
-					       SCSI_SENSE_BUFFERSIZE);
+					       sizeof(tapeDCDB->sense_info), 0);
 				} else {
-					memcpy(scb->scsi_cmd->sense_buffer,
+					memcpy_and_pad(scb->scsi_cmd->sense_buffer,
+					       SCSI_SENSE_BUFFERSIZE,
 					       scb->dcdb.sense_info,
-					       SCSI_SENSE_BUFFERSIZE);
+					       sizeof(scb->dcdb.sense_info), 0);
 				}
 				device_error = 2;	/* check condition */
 			}
-- 
2.25.1

Re: [PATCH] scsi: ips: Avoid over-read of sense buffer

[Martin K. Petersen]

Kees,

> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy() avoid intentionally reading across
> neighboring array fields.

Applied to 5.14/scsi-staging, thanks!

Strictly speaking padding shouldn't be necessary but this isn't fast
path so no big deal.

-- 
Martin K. Petersen	Oracle Linux Engineering