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From:   gregkh@linuxfoundation.org
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ian Abbott <abbotti@mev.co.uk>
Subject: [PATCH 4.4 52/75] staging: comedi: das6402: Fix endian problem for AI command data
Date:   Mon, 15 Mar 2021 14:52:06 +0100
Message-Id: <20210315135209.948354567@linuxfoundation.org>
In-Reply-To: <20210315135208.252034256@linuxfoundation.org>
References: <20210315135208.252034256@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

commit 1c0f20b78781b9ca50dc3ecfd396d0db5b141890 upstream.

The analog input subdevice supports Comedi asynchronous commands that
use Comedi's 16-bit sample format.  However, the call to
`comedi_buf_write_samples()` is 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 variable
holding the sample value to `unsigned short`.

Fixes: d1d24cb65ee3 ("staging: comedi: das6402: read analog input samples in interrupt handler")
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20210223143055.257402-5-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/comedi/drivers/das6402.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/comedi/drivers/das6402.c
+++ b/drivers/staging/comedi/drivers/das6402.c
@@ -193,7 +193,7 @@ static irqreturn_t das6402_interrupt(int
 	if (status & DAS6402_STATUS_FFULL) {
 		async->events |= COMEDI_CB_OVERFLOW;
 	} else if (status & DAS6402_STATUS_FFNE) {
-		unsigned int val;
+		unsigned short val;
 
 		val = das6402_ai_read_sample(dev, s);
 		comedi_buf_write_samples(s, &val, 1);