From 11e7a91994c29da96d847f676be023da6a2c1359 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Wed, 27 May 2020 21:48:30 +0300
Subject: [PATCH] airo: Fix read overflows sending packets
Git-commit: 11e7a91994c29da96d847f676be023da6a2c1359
Patch-mainline: v5.8-rc1
References: git-fixes

The problem is that we always copy a minimum of ETH_ZLEN (60) bytes from
skb->data even when skb->len is less than ETH_ZLEN so it leads to a read
overflow.

The fix is to pad skb->data to at least ETH_ZLEN bytes.

Cc: <stable@vger.kernel.org>
Reported-by: Hu Jiahui <kirin.say@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200527184830.GA1164846@mwanda
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/cisco/airo.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
index 8363f91df7ea..827bb6d74815 100644
--- a/drivers/net/wireless/cisco/airo.c
+++ b/drivers/net/wireless/cisco/airo.c
@@ -1925,6 +1925,10 @@ static netdev_tx_t mpi_start_xmit(struct sk_buff *skb,
 		airo_print_err(dev->name, "%s: skb == NULL!",__func__);
 		return NETDEV_TX_OK;
 	}
+	if (skb_padto(skb, ETH_ZLEN)) {
+		dev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
 	npacks = skb_queue_len (&ai->txq);
 
 	if (npacks >= MAXTXQ - 1) {
@@ -2127,6 +2131,10 @@ static netdev_tx_t airo_start_xmit(struct sk_buff *skb,
 		airo_print_err(dev->name, "%s: skb == NULL!", __func__);
 		return NETDEV_TX_OK;
 	}
+	if (skb_padto(skb, ETH_ZLEN)) {
+		dev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
 
 	/* Find a vacant FID */
 	for( i = 0; i < MAX_FIDS / 2 && (fids[i] & 0xffff0000); i++ );
@@ -2201,6 +2209,10 @@ static netdev_tx_t airo_start_xmit11(struct sk_buff *skb,
 		airo_print_err(dev->name, "%s: skb == NULL!", __func__);
 		return NETDEV_TX_OK;
 	}
+	if (skb_padto(skb, ETH_ZLEN)) {
+		dev->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
 
 	/* Find a vacant FID */
 	for( i = MAX_FIDS / 2; i < MAX_FIDS && (fids[i] & 0xffff0000); i++ );
-- 
2.16.4