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

[Kees Cook]

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 <keesc...@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