3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Salido <salidoa@xxxxxxxxxx> commit 4617f564c06117c7d1b611be49521a4430042287 upstream. When calling a dm ioctl that doesn't process any data (IOCTL_FLAGS_NO_PARAMS), the contents of the data field in struct dm_ioctl are left initialized. Current code is incorrectly extending the size of data copied back to user, causing the contents of kernel stack to be leaked to user. Fix by only copying contents before data and allow the functions processing the ioctl to override. Signed-off-by: Adrian Salido <salidoa@xxxxxxxxxx> Reviewed-by: Alasdair G Kergon <agk@xxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- drivers/md/dm-ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1839,7 +1839,7 @@ static int ctl_ioctl(uint command, struc if (r) goto out; - param->data_size = sizeof(*param); + param->data_size = offsetof(struct dm_ioctl, data); r = fn(param, input_param_size); if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&