On 25/10/2021 12:45, Johan Hovold wrote:
USB transfer buffers are typically mapped for DMA and must not be
allocated on the stack or transfers will fail.
Allocate proper transfer buffers in the various command helpers and
return an error on short transfers instead of acting on random stack
data.
Note that this also fixes a stack info leak on systems where DMA is not
used as 32 bytes are always sent to the device regardless of how short
the command is.
Fixes: 63274cd7d38a ("Staging: comedi: add usb dt9812 driver")
Cc: stable@xxxxxxxxxxxxxxx # 2.6.29
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
drivers/comedi/drivers/dt9812.c | 109 ++++++++++++++++++++++++--------
1 file changed, 82 insertions(+), 27 deletions(-)
diff --git a/drivers/comedi/drivers/dt9812.c b/drivers/comedi/drivers/dt9812.c
index 634f57730c1e..f15c306f2d06 100644
--- a/drivers/comedi/drivers/dt9812.c
+++ b/drivers/comedi/drivers/dt9812.c
@@ -32,6 +32,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/errno.h>
+#include <linux/slab.h>
#include <linux/uaccess.h>
#include "../comedi_usb.h"
@@ -237,22 +238,41 @@ static int dt9812_read_info(struct comedi_device *dev,
{
struct usb_device *usb = comedi_to_usb_dev(dev);
struct dt9812_private *devpriv = dev->private;
- struct dt9812_usb_cmd cmd;
+ struct dt9812_usb_cmd *cmd;
int count, ret;
+ u8 *tbuf;
- cmd.cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
- cmd.u.flash_data_info.address =
+ cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+ if (!cmd)
+ return -ENOMEM;
+
+ cmd->cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
+ cmd->u.flash_data_info.address =
cpu_to_le16(DT9812_DIAGS_BOARD_INFO_ADDR + offset);
- cmd.u.flash_data_info.numbytes = cpu_to_le16(buf_size);
+ cmd->u.flash_data_info.numbytes = cpu_to_le16(buf_size);
/* DT9812 only responds to 32 byte writes!! */
ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
- &cmd, 32, &count, DT9812_USB_TIMEOUT);
+ cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+ kfree(cmd);
if (ret)
return ret;
- return usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
- buf, buf_size, &count, DT9812_USB_TIMEOUT);
+ tbuf = kmalloc(buf_size, GFP_KERNEL);
+ if (!tbuf)
+ return -ENOMEM;
+
+ ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
+ tbuf, buf_size, &count, DT9812_USB_TIMEOUT);
+ if (!ret) {
+ if (count == buf_size)
+ memcpy(buf, tbuf, buf_size);
+ else
+ ret = -EREMOTEIO;
+ }
+ kfree(tbuf);
+
+ return ret;
}
I suggest doing all the allocations up front so it doesn't leave an
unread reply message in the unlikely event that the tbuf allocation
fails. (It could even allocate a single buffer for both the command and
the reply since they are not needed at the same time.)
Ditto for the other functions in the patch.
--
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