mac80211: fils_aead: fix encrypt error handling

gcc -Wmaybe-uninitialized reports a bug in aes_siv_encryp:

net/mac80211/fils_aead.c: In function ‘aes_siv_encrypt.constprop’:
net/mac80211/fils_aead.c:84:26: error: ‘tfm2’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

At the time that the memory allocation fails, 'tfm2' has not been
allocated, so we should not attempt to free it later, and we can
simply return an error.

Fixes: 39404fee ("mac80211: FILS AEAD protection for station mode association frames")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/fils_aead.c

@@ -110,10 +110,8 @@ static int aes_siv_encrypt(const u8 *key, size_t key_len,
 	 * overwriting this during AES-CTR.
 	 */
 	tmp = kmemdup(plain, plain_len, GFP_KERNEL);
-	if (!tmp) {
-		res = -ENOMEM;
-		goto fail;
-	}
+	if (!tmp)
+		return -ENOMEM;
 
 	/* IV for CTR before encrypted data */
 	memcpy(out, v, AES_BLOCK_SIZE);