tree 23f09ff365e82104797fc0dccb9084c4eef0088d
parent 6f73fbcec27be8b074555e18d9f50c3013e4d802
author Ian Abbott <abbotti@mev.co.uk> 1348079859 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1348244993 -0700

staging: comedi: 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associated with the channel list is no longer valid.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.

Note that `cleanup_device()` could be called at an inappropriate time
while the comedi device is open, but that's a separate bug not related
to this this patch.

Cc: stable@vger.kernel.org
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>