linux-kernel - [PATCH 5.1 120/121] mac80211: Do not use stack memory with scatterlist for GMAC

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Message-Id: <20190624092326.739934714@linuxfoundation.org>
Date:   Mon, 24 Jun 2019 17:57:32 +0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jouni Malinen <j@...fi>,
        Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 5.1 120/121] mac80211: Do not use stack memory with scatterlist for GMAC

From: Jouni Malinen <j@...fi>

commit a71fd9dac23613d96ba3c05619a8ef4fd6cdf9b9 upstream.

ieee80211_aes_gmac() uses the mic argument directly in sg_set_buf() and
that does not allow use of stack memory (e.g., BUG_ON() is hit in
sg_set_buf() with CONFIG_DEBUG_SG). BIP GMAC TX side is fine for this
since it can use the skb data buffer, but the RX side was using a stack
variable for deriving the local MIC value to compare against the
received one.

Fix this by allocating heap memory for the mic buffer.

This was found with hwsim test case ap_cipher_bip_gmac_128 hitting that
BUG_ON() and kernel panic.

Cc: stable@...r.kernel.org
Signed-off-by: Jouni Malinen <j@...fi>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/mac80211/wpa.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -1175,7 +1175,7 @@ ieee80211_crypto_aes_gmac_decrypt(struct
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 	struct ieee80211_key *key = rx->key;
 	struct ieee80211_mmie_16 *mmie;
-	u8 aad[GMAC_AAD_LEN], mic[GMAC_MIC_LEN], ipn[6], nonce[GMAC_NONCE_LEN];
+	u8 aad[GMAC_AAD_LEN], *mic, ipn[6], nonce[GMAC_NONCE_LEN];
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 
 	if (!ieee80211_is_mgmt(hdr->frame_control))
@@ -1206,13 +1206,18 @@ ieee80211_crypto_aes_gmac_decrypt(struct
 		memcpy(nonce, hdr->addr2, ETH_ALEN);
 		memcpy(nonce + ETH_ALEN, ipn, 6);
 
+		mic = kmalloc(GMAC_MIC_LEN, GFP_ATOMIC);
+		if (!mic)
+			return RX_DROP_UNUSABLE;
 		if (ieee80211_aes_gmac(key->u.aes_gmac.tfm, aad, nonce,
 				       skb->data + 24, skb->len - 24,
 				       mic) < 0 ||
 		    crypto_memneq(mic, mmie->mic, sizeof(mmie->mic))) {
 			key->u.aes_gmac.icverrors++;
+			kfree(mic);
 			return RX_DROP_UNUSABLE;
 		}
+		kfree(mic);
 	}
 
 	memcpy(key->u.aes_gmac.rx_pn, ipn, 6);