[PATCH net] net: enetc: check the number of BDs needed for xdp_frame

[wei . fang]

From: Wei Fang <wei.fang@xxxxxxx>

The size of xdp_redirect_arr array is ENETC_MAX_SKB_FRAGS. However, the
number of fragments contained in xdp_frame may be greater than or equal
to ENETC_MAX_SKB_FRAGS, which will cause the access to xdp_redirect_arr
to be out of bounds.

Fixes: 9d2b68cc108d ("net: enetc: add support for XDP_REDIRECT")
Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
---
 drivers/net/ethernet/freescale/enetc/enetc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index aa8a87124b10..8e3f345dd9aa 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -1783,6 +1783,7 @@ int enetc_xdp_xmit(struct net_device *ndev, int num_frames,
 {
 	struct enetc_tx_swbd xdp_redirect_arr[ENETC_MAX_SKB_FRAGS] = {0};
 	struct enetc_ndev_priv *priv = netdev_priv(ndev);
+	struct skb_shared_info *shinfo;
 	struct enetc_bdr *tx_ring;
 	int xdp_tx_bd_cnt, i, k;
 	int xdp_tx_frm_cnt = 0;
@@ -1798,6 +1799,12 @@ int enetc_xdp_xmit(struct net_device *ndev, int num_frames,
 	prefetchw(ENETC_TXBD(*tx_ring, tx_ring->next_to_use));
 
 	for (k = 0; k < num_frames; k++) {
+		if (xdp_frame_has_frags(frames[k])) {
+			shinfo = xdp_get_shared_info_from_frame(frames[k]);
+			if (unlikely((shinfo->nr_frags + 1) > ENETC_MAX_SKB_FRAGS))
+				break;
+		}
+
 		xdp_tx_bd_cnt = enetc_xdp_frame_to_xdp_tx_swbd(tx_ring,
 							       xdp_redirect_arr,
 							       frames[k]);
-- 
2.34.1