[PATCH 5/6] libata-scsi: Move sense buffers onto stack

Kees Cook
2018-05-22T18:15:37Z

Instead of dynamically allocating the sense buffers, put them on the
stack so that future compile-time sizeof() checks will be able to see
their buffer length.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/ata/libata-scsi.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 89a9d4a2efc8..3a43d3a1ce2d 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -597,8 +597,9 @@ static int ata_get_identity(struct ata_port *ap, struct scsi_device *sdev,
int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
{
int rc = 0;
+ u8 sensebuf[SCSI_SENSE_BUFFERSIZE];
u8 scsi_cmd[MAX_COMMAND_SIZE];
- u8 args[4], *argbuf = NULL, *sensebuf = NULL;
+ u8 args[4], *argbuf = NULL;
int argsize = 0;
enum dma_data_direction data_dir;
struct scsi_sense_hdr sshdr;
@@ -610,10 +611,7 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
if (copy_from_user(args, arg, sizeof(args)))
return -EFAULT;

- sensebuf = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
- if (!sensebuf)
- return -ENOMEM;
-
+ memset(sensebuf, 0, sizeof(sensebuf));
memset(scsi_cmd, 0, sizeof(scsi_cmd));

if (args[3]) {
@@ -685,7 +683,6 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
&& copy_to_user(arg + sizeof(args), argbuf, argsize))
rc = -EFAULT;
error:
- kfree(sensebuf);
kfree(argbuf);
return rc;
}
@@ -704,8 +701,9 @@ int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg)
int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg)
{
int rc = 0;
+ u8 sensebuf[SCSI_SENSE_BUFFERSIZE];
u8 scsi_cmd[MAX_COMMAND_SIZE];
- u8 args[7], *sensebuf = NULL;
+ u8 args[7];
struct scsi_sense_hdr sshdr;
int cmd_result;

@@ -715,10 +713,7 @@ int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg)
if (copy_from_user(args, arg, sizeof(args)))
return -EFAULT;

- sensebuf = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
- if (!sensebuf)
- return -ENOMEM;
-
+ memset(sensebuf, 0, sizeof(sensebuf));
memset(scsi_cmd, 0, sizeof(scsi_cmd));
scsi_cmd[0] = ATA_16;
scsi_cmd[1] = (3 << 1); /* Non-data */
@@ -769,7 +764,6 @@ int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg)
}

error:
- kfree(sensebuf);
return rc;
}

--
2.17.0