kstrdup() returns NULL when some internal memory errors happen, it is better to check the return value of it. Otherwise, we may not to be able to catch some memory errors in time. Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com> Link: https://lore.kernel.org/r/tencent_1E3950293AC22395ACFE99404C985D738309@qq.com Signed-off-by: Takashi Iwai <tiwai@suse.de>