From a6451192da2691dcf39507bd758dde35d4606ee1 Mon Sep 17 00:00:00 2001 From: Song Yoong Siang Date: Wed, 25 Aug 2021 08:55:29 +0800 Subject: net: stmmac: fix kernel panic due to NULL pointer dereference of xsk_pool After free xsk_pool, there is possibility that napi polling is still running in the middle, thus causes a kernel crash due to kernel NULL pointer dereference of rx_q->xsk_pool and tx_q->xsk_pool. Fix this by changing the XDP pool setup sequence to: 1. disable napi before free xsk_pool 2. enable napi after init xsk_pool The following kernel panic is observed without this patch: RIP: 0010:xsk_uses_need_wakeup+0x5/0x10 Call Trace: stmmac_napi_poll_rxtx+0x3a9/0xae0 [stmmac] __napi_poll+0x27/0x130 net_rx_action+0x233/0x280 __do_softirq+0xe2/0x2b6 run_ksoftirqd+0x1a/0x20 smpboot_thread_fn+0xac/0x140 ? sort_range+0x20/0x20 kthread+0x124/0x150 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x1f/0x30 ---[ end trace a77c8956b79ac107 ]--- Fixes: bba2556efad6 ("net: stmmac: Enable RX via AF_XDP zero-copy") Cc: # 5.13.x Signed-off-by: Song Yoong Siang Signed-off-by: David S. Miller --- drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'drivers/net/ethernet/stmicro') diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c index 105821b53020..2a616c6f7cd0 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c @@ -34,18 +34,18 @@ static int stmmac_xdp_enable_pool(struct stmmac_priv *priv, need_update = netif_running(priv->dev) && stmmac_xdp_is_enabled(priv); if (need_update) { - stmmac_disable_rx_queue(priv, queue); - stmmac_disable_tx_queue(priv, queue); napi_disable(&ch->rx_napi); napi_disable(&ch->tx_napi); + stmmac_disable_rx_queue(priv, queue); + stmmac_disable_tx_queue(priv, queue); } set_bit(queue, priv->af_xdp_zc_qps); if (need_update) { - napi_enable(&ch->rxtx_napi); stmmac_enable_rx_queue(priv, queue); stmmac_enable_tx_queue(priv, queue); + napi_enable(&ch->rxtx_napi); err = stmmac_xsk_wakeup(priv->dev, queue, XDP_WAKEUP_RX); if (err) @@ -72,10 +72,10 @@ static int stmmac_xdp_disable_pool(struct stmmac_priv *priv, u16 queue) need_update = netif_running(priv->dev) && stmmac_xdp_is_enabled(priv); if (need_update) { + napi_disable(&ch->rxtx_napi); stmmac_disable_rx_queue(priv, queue); stmmac_disable_tx_queue(priv, queue); synchronize_rcu(); - napi_disable(&ch->rxtx_napi); } xsk_pool_dma_unmap(pool, STMMAC_RX_DMA_ATTR); @@ -83,10 +83,10 @@ static int stmmac_xdp_disable_pool(struct stmmac_priv *priv, u16 queue) clear_bit(queue, priv->af_xdp_zc_qps); if (need_update) { - napi_enable(&ch->rx_napi); - napi_enable(&ch->tx_napi); stmmac_enable_rx_queue(priv, queue); stmmac_enable_tx_queue(priv, queue); + napi_enable(&ch->rx_napi); + napi_enable(&ch->tx_napi); } return 0; -- cgit v1.2.3-59-g8ed1b