From: Xiyu Yang xiyuyang19@fudan.edu.cn
commit 332e0e17ad49e084b7db670ef43b5eb59abd9e34 upstream.
comedi_open() invokes comedi_dev_get_from_minor(), which returns a reference of the COMEDI device to "dev" with increased refcount.
When comedi_open() returns, "dev" becomes invalid, so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of comedi_open(). When "cfp" allocation is failed, the refcnt increased by comedi_dev_get_from_minor() is not decreased, causing a refcnt leak.
Fix this issue by calling comedi_dev_put() on this error path when "cfp" allocation is failed.
Fixes: 20f083c07565 ("staging: comedi: prepare support for per-file read and write subdevices") Signed-off-by: Xiyu Yang xiyuyang19@fudan.edu.cn Cc: stable stable@vger.kernel.org Signed-off-by: Xin Tan tanxin.ctf@gmail.com Signed-off-by: Ian Abbott abbotti@mev.co.uk Link: https://lore.kernel.org/r/1587361459-83622-1-git-send-email-xiyuyang19@fudan... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/staging/comedi/comedi_fops.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2592,8 +2592,10 @@ static int comedi_open(struct inode *ino }
cfp = kzalloc(sizeof(*cfp), GFP_KERNEL); - if (!cfp) + if (!cfp) { + comedi_dev_put(dev); return -ENOMEM; + }
cfp->dev = dev;