From: Ian Abbott <abbotti@mev.co.uk>
Date: Fri, 28 Sep 2012 12:06:54 +0000 (+0100)
Subject: Fix memory leak for saved channel list
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=62149c2a160abe17fa1fa4cb4af65a12171f3163;p=comedi.git

Fix memory leak for saved channel list

When `do_cmd_ioctl()` allocates memory for the kernel copy of a channel
list, it frees any previously allocated channel list in
`async->cmd.chanlist` and replaces it with the new one.  However, if the
device is ever removed (or "detached") the cleanup code in
`cleanup_device()` in "drivers.c" does not free this memory so it is
lost.

A sensible place to free the kernel copy of the channel list is in
`do_become_nonbusy()` as at that point the comedi asynchronous command
associated with the channel list is no longer valid.  Free the channel
list in `do_become_nonbusy()` instead of `do_cmd_ioctl()` and clear the
pointer to prevent it being freed more than once.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
---

diff --git a/comedi/comedi_fops.c b/comedi/comedi_fops.c
index d4e209db..5f64100c 100644
--- a/comedi/comedi_fops.c
+++ b/comedi/comedi_fops.c
@@ -1129,8 +1129,6 @@ static int do_cmd_ioctl(comedi_device * dev, comedi_cmd __user *arg, void *file)
 		goto cleanup;
 	}
 
-	if (async->cmd.chanlist)
-		kfree(async->cmd.chanlist);
 	async->cmd = user_cmd;
 	async->cmd.data = NULL;
 	/* load channel/gain list */
@@ -1873,6 +1871,8 @@ void do_become_nonbusy(comedi_device * dev, comedi_subdevice * s)
 	if (async) {
 		comedi_reset_async_buf(async);
 		async->inttrig = NULL;
+		kfree(async->cmd.chanlist);
+		async->cmd.chanlist = NULL;
 	} else {
 		printk("BUG: (?) do_become_nonbusy called with async=0\n");
 	}