Buffer overflow could occur in the loop "while", due to accessing an
array element before checking the index.

Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Daniil Dementev <d.dementev@ispras.ru>
Reviewed-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Link: https://lore.kernel.org/r/20220610165732.2904-1-d.dementev@ispras.ruSigned-off-by: Takashi Iwai <tiwai@suse.de>