wifi: brcmfmac: cfg80211: Pass the PMK in binary instead of hex

Apparently the hex passphrase mechanism does not work on newer
chips/firmware (e.g. BCM4387). It seems there was a simple way of
passing it in binary all along, so use that and avoid the hexification.

OpenBSD has been doing it like this from the beginning, so this should
work on all chips.

Also clear the structure before setting the PMK. This was leaking
uninitialized stack contents to the device.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230214092423.15175-6-marcan@marcan.st

drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c

@@ -1686,13 +1686,14 @@ static int brcmf_set_pmk(struct brcmf_if *ifp, const u8 *pmk_data, u16 pmk_len)
 {
 	struct brcmf_pub *drvr = ifp->drvr;
 	struct brcmf_wsec_pmk_le pmk;
-	int i, err;
+	int err;
+
+	memset(&pmk, 0, sizeof(pmk));
 
-	/* convert to firmware key format */
-	pmk.key_len = cpu_to_le16(pmk_len << 1);
-	pmk.flags = cpu_to_le16(BRCMF_WSEC_PASSPHRASE);
-	for (i = 0; i < pmk_len; i++)
-		snprintf(&pmk.key[2 * i], 3, "%02x", pmk_data[i]);
+	/* pass pmk directly */
+	pmk.key_len = cpu_to_le16(pmk_len);
+	pmk.flags = cpu_to_le16(0);
+	memcpy(pmk.key, pmk_data, pmk_len);
 
 	/* store psk in firmware */
 	err = brcmf_fil_cmd_data_set(ifp, BRCMF_C_SET_WSEC_PMK,