netdev - [PATCH 1/1] ionic: fix array overflow on receiving too many fragments for a packet

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Date:   Sun,  6 Dec 2020 21:35:37 +0800
From:   Xiaohui Zhang <ruc_zhangxiaohui@....com>
To:     Xiaohui Zhang <ruc_zhangxiaohui@....com>,
        Shannon Nelson <snelson@...sando.io>,
        Pensando Drivers <drivers@...sando.io>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] ionic: fix array overflow on receiving too many fragments for a packet

From: Zhang Xiaohui <ruc_zhangxiaohui@....com>

If the hardware receives an oversized packet with too many rx fragments,
skb_shinfo(skb)->frags can overflow and corrupt memory of adjacent pages.
This becomes especially visible if it corrupts the freelist pointer of
a slab page.

Signed-off-by: Zhang Xiaohui <ruc_zhangxiaohui@....com>
---
 drivers/net/ethernet/pensando/ionic/ionic_txrx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index 169ac4f54..a3e274c65 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -102,8 +102,12 @@ static struct sk_buff *ionic_rx_frags(struct ionic_queue *q,
 
 		dma_unmap_page(dev, dma_unmap_addr(page_info, dma_addr),
 			       PAGE_SIZE, DMA_FROM_DEVICE);
-		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+		struct skb_shared_info *shinfo = skb_shinfo(skb);
+
+		if (shinfo->nr_frags < ARRAY_SIZE(shinfo->frags)) {
+			skb_add_rx_frag(skb, shinfo->nr_frags,
 				page_info->page, 0, frag_len, PAGE_SIZE);
+		}
 		page_info->page = NULL;
 		page_info++;
 		i--;
-- 
2.17.1