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It uses: tx_packets = (tx_q->cur_tx + 1) - first_tx; however, these are indexes into a circular buffer, so cur_tx can be less than first_tx, and when that happens, tx_packets becomes a very large unsigned integer. When this is added to tx_q->tx_count_frames, it has the effect of reducing the count of frames, possibly causing it to also wrap to a very large unsigned integer. Fix this by using CIRC_CNT() to calculate the number of descriptors used. Signed-off-by: Russell King (Oracle) Reviewed-by: Simon Horman Link: https://patch.msgid.link/E1vuoIl-0000000Aouz-0ttb@rmk-PC.armlinux.org.uk Signed-off-by: Jakub Kicinski [ Upstream commit dd53a0e85969c6b2a5a4e4e46ba05b3187231017 ] --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 81a6ab19a45b..0266b09f0faf 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -14,6 +14,7 @@ https://bugzilla.stlinux.com/ *******************************************************************************/ +#include #include #include #include @@ -4511,7 +4512,8 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) tx_q->tx_skbuff_dma[tx_q->cur_tx].buf_type = STMMAC_TXBUF_T_SKB; /* Manage tx mitigation */ - tx_packets = (tx_q->cur_tx + 1) - first_tx; + tx_packets = CIRC_CNT(tx_q->cur_tx + 1, first_tx, + priv->dma_conf.dma_tx_size); tx_q->tx_count_frames += tx_packets; if ((skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) && priv->hwts_tx_en) @@ -4789,7 +4791,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) * This approach takes care about the fragments: desc is the first * element in case of no SG. */ - tx_packets = (entry + 1) - first_tx; + tx_packets = CIRC_CNT(entry + 1, first_tx, priv->dma_conf.dma_tx_size); tx_q->tx_count_frames += tx_packets; if ((skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) && priv->hwts_tx_en) -- 2.53.0