From f739850941bc300ed4dc18e22d42cbb670bf69b6 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@mev.co.uk>
Date: Thu, 30 Oct 2014 12:42:30 +0000
Subject: [PATCH] staging: comedi: don't allow write() on async command set up
for "read"
If a Comedi asynchronous command has been set up for data transfer in
the "read" direction on the current "write" subdevice (for those
subdevices that support both directions), don't allow the "write" file
operation as that would mess with the data in the comedi data buffer
that is written by the low-level comedi hardware driver.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/staging/comedi/comedi_fops.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 452121b6a604f..0ed6f1f00e7fc 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2075,6 +2075,10 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
retval = -EACCES;
goto out;
}
+ if (!(async->cmd.flags & CMDF_WRITE)) {
+ retval = -EINVAL;
+ goto out;
+ }
add_wait_queue(&async->wait_head, &wait);
on_wait_queue = true;
@@ -2146,6 +2150,10 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
retval = -EACCES;
break;
}
+ if (!(async->cmd.flags & CMDF_WRITE)) {
+ retval = -EINVAL;
+ break;
+ }
continue;
}
--
2.30.2