linux-kernel - [PATCH 4.9 53/78] staging: comedi: adv_pci1710: Fix endian problem for AI command data

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Date:   Mon, 15 Mar 2021 14:52:16 +0100
From:   gregkh@...uxfoundation.org
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ian Abbott <abbotti@....co.uk>
Subject: [PATCH 4.9 53/78] staging: comedi: adv_pci1710: Fix endian problem for AI command data

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

From: Ian Abbott <abbotti@....co.uk>

commit b2e78630f733a76508b53ba680528ca39c890e82 upstream.

The analog input subdevice supports Comedi asynchronous commands that
use Comedi's 16-bit sample format.  However, the calls to
`comedi_buf_write_samples()` are passing the address of a 32-bit integer
variable.  On bigendian machines, this will copy 2 bytes from the wrong
end of the 32-bit value.  Fix it by changing the type of the variables
holding the sample value to `unsigned short`.  The type of the `val`
parameter of `pci1710_ai_read_sample()` is changed to `unsigned short *`
accordingly.  The type of the `val` variable in `pci1710_ai_insn_read()`
is also changed to `unsigned short` since its address is passed to
`pci1710_ai_read_sample()`.

Fixes: a9c3a015c12f ("staging: comedi: adv_pci1710: use comedi_buf_write_samples()")
Cc: <stable@...r.kernel.org> # 4.0+
Signed-off-by: Ian Abbott <abbotti@....co.uk>
Link: https://lore.kernel.org/r/20210223143055.257402-4-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/staging/comedi/drivers/adv_pci1710.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/staging/comedi/drivers/adv_pci1710.c
+++ b/drivers/staging/comedi/drivers/adv_pci1710.c
@@ -299,11 +299,11 @@ static int pci1710_ai_eoc(struct comedi_
 static int pci1710_ai_read_sample(struct comedi_device *dev,
 				  struct comedi_subdevice *s,
 				  unsigned int cur_chan,
-				  unsigned int *val)
+				  unsigned short *val)
 {
 	const struct boardtype *board = dev->board_ptr;
 	struct pci1710_private *devpriv = dev->private;
-	unsigned int sample;
+	unsigned short sample;
 	unsigned int chan;
 
 	sample = inw(dev->iobase + PCI171X_AD_DATA_REG);
@@ -344,7 +344,7 @@ static int pci1710_ai_insn_read(struct c
 	pci1710_ai_setup_chanlist(dev, s, &insn->chanspec, 1, 1);
 
 	for (i = 0; i < insn->n; i++) {
-		unsigned int val;
+		unsigned short val;
 
 		/* start conversion */
 		outw(0, dev->iobase + PCI171X_SOFTTRG_REG);
@@ -394,7 +394,7 @@ static void pci1710_handle_every_sample(
 {
 	struct comedi_cmd *cmd = &s->async->cmd;
 	unsigned int status;
-	unsigned int val;
+	unsigned short val;
 	int ret;
 
 	status = inw(dev->iobase + PCI171X_STATUS_REG);
@@ -454,7 +454,7 @@ static void pci1710_handle_fifo(struct c
 	}
 
 	for (i = 0; i < devpriv->max_samples; i++) {
-		unsigned int val;
+		unsigned short val;
 		int ret;
 
 		ret = pci1710_ai_read_sample(dev, s, s->async->cur_chan, &val);