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staging: comedi: fix result of memdup_user for user chanlist

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If the channel list is not set in userspace we get an error at
PTR_ERR(async->cmd.chanlist). However, do_become_nonbusy(dev, s) cleans
up this pointer which causes a kernel ooops. Setting the channel list in
async to NULL and checking this in do_become_nonbusy prevents the oops.

[Ian Abbott] Also do the same for the chanlist allocated in
do_cmdtest_ioctl().

Signed-off-by: Bernd Porr <mail@berndporr.me.uk>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bernd Porr 2013-12-11 16:06:15 +00:00 committed by Greg Kroah-Hartman
parent b163970fa5
commit e56b140105
1 changed files with 2 additions and 0 deletions
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2
drivers/staging/comedi/comedi_fops.c
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@ -1473,6 +1473,7 @@ static int do_cmd_ioctl(struct comedi_device *dev,
async->cmd.chanlist_len * sizeof(int));
if (IS_ERR(async->cmd.chanlist)) {
ret = PTR_ERR(async->cmd.chanlist);
async->cmd.chanlist = NULL;
dev_dbg(dev->class_dev, "memdup_user failed with code %d\n",
ret);
goto cleanup;
@ -1595,6 +1596,7 @@ static int do_cmdtest_ioctl(struct comedi_device *dev,
cmd.chanlist_len * sizeof(int));
if (IS_ERR(chanlist)) {
ret = PTR_ERR(chanlist);
chanlist = NULL;
dev_dbg(dev->class_dev,
"memdup_user exited with code %d", ret);
goto cleanup;