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list is in `do_become_nonbusy()` as at that point the comedi asynchronous command associated with the channel list is no longer valid.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: [email protected] Signed-off-by: Ian Abbott <[email protected]> --- drivers/staging/comedi/comedi_fops.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 9ef32b8..a2efe74 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1195,7 +1195,6 @@ static int do_cmd_ioctl(struct comedi_device *dev, goto cleanup; } - kfree(async->cmd.chanlist); async->cmd = cmd; async->cmd.data = NULL; /* load channel/gain list */ @@ -2025,6 +2024,8 @@ static void do_become_nonbusy(struct comedi_device *dev, if (async) { comedi_reset_async_buf(async); async->inttrig = NULL; + kfree(async->cmd.chanlist); + async->cmd.chanlist = NULL; } else { dev_err(dev->class_dev, "BUG: (?) do_become_nonbusy called with async=NULL\n"); -- 1.7.12 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
