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From: Huai-Yuan Liu <qq810974084@gmail.com>
To: jes@trained-monkey.org,
	davem@davemloft.net,
	edumazet@google.com,
	kuba@kernel.org,
	pabeni@redhat.com
Cc: linux-hippi@sunsite.dk,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	baijiaju1990@gmail.com,
	Huai-Yuan Liu <qq810974084@gmail.com>
Subject: [PATCH] hippi: fix possible buffer overflow caused by bad DMA value in rr_start_xmit()
Date: Wed, 12 Jun 2024 17:31:53 +0800
Message-Id: <20240612093153.297167-1-qq810974084@gmail.com>
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The value rrpriv->info->tx_ctrl is stored in DMA memory, and it is
assigned to txctrl, so txctrl->pi can be modified at any time by malicious
hardware. Becausetxctrl->pi is assigned to index, buffer overflow may
occur when the code "rrpriv->tx_skbuff[index]" is executed.

To address this issue, the index should be checked.

Fixes: f33a7251c825 ("hippi: switch from 'pci_' to 'dma_' API")
Signed-off-by: Huai-Yuan Liu <qq810974084@gmail.com>
---
 drivers/net/hippi/rrunner.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/hippi/rrunner.c b/drivers/net/hippi/rrunner.c
index aa8f828a0ae7..184f0933bca0 100644
--- a/drivers/net/hippi/rrunner.c
+++ b/drivers/net/hippi/rrunner.c
@@ -1440,6 +1440,11 @@ static netdev_tx_t rr_start_xmit(struct sk_buff *skb,
 	txctrl = &rrpriv->info->tx_ctrl;
 
 	index = txctrl->pi;
+	if (index < 0 || index >= TX_RING_ENTRIES) {
+		printk("invalid index value %02x\n", index);
+		spin_unlock_irqrestore(&rrpriv->lock, flags);
+		return NETDEV_TX_BUSY;
+	}
 
 	rrpriv->tx_skbuff[index] = skb;
 	set_rraddr(&rrpriv->tx_ring[index].addr,
-- 
2.34.1