[PATCH AUTOSEL 5.4 17/23] bridge: Fix possible races between assigning rx_handler_data and setting IFF_BRIDGE_PORT bit

[PATCH AUTOSEL 5.4 17/23] bridge: Fix possible races between assigning rx_handler_data and setting IFF_BRIDGE_PORT bit

[Sasha Levin]

From: Zhang Zhengming <zhangzhengming@huawei.com>

[ Upstream commit 59259ff7a81b9eb6213891c6451221e567f8f22f ]

There is a crash in the function br_get_link_af_size_filtered,
as the port_exists(dev) is true and the rx_handler_data of dev is NULL.
But the rx_handler_data of dev is correct saved in vmcore.

The oops looks something like:
 ...
 pc : br_get_link_af_size_filtered+0x28/0x1c8 [bridge]
 ...
 Call trace:
  br_get_link_af_size_filtered+0x28/0x1c8 [bridge]
  if_nlmsg_size+0x180/0x1b0
  rtnl_calcit.isra.12+0xf8/0x148
  rtnetlink_rcv_msg+0x334/0x370
  netlink_rcv_skb+0x64/0x130
  rtnetlink_rcv+0x28/0x38
  netlink_unicast+0x1f0/0x250
  netlink_sendmsg+0x310/0x378
  sock_sendmsg+0x4c/0x70
  __sys_sendto+0x120/0x150
  __arm64_sys_sendto+0x30/0x40
  el0_svc_common+0x78/0x130
  el0_svc_handler+0x38/0x78
  el0_svc+0x8/0xc

In br_add_if(), we found there is no guarantee that
assigning rx_handler_data to dev->rx_handler_data
will before setting the IFF_BRIDGE_PORT bit of priv_flags.
So there is a possible data competition:

CPU 0:                                                        CPU 1:
(RCU read lock)                                               (RTNL lock)
rtnl_calcit()                                                 br_add_slave()
  if_nlmsg_size()                                               br_add_if()
    br_get_link_af_size_filtered()                              -> netdev_rx_handler_register
                                                                    ...
                                                                    // The order is not guaranteed
      ...                                                           -> dev->priv_flags |= IFF_BRIDGE_PORT;
      // The IFF_BRIDGE_PORT bit of priv_flags has been set
      -> if (br_port_exists(dev)) {
        // The dev->rx_handler_data has NOT been assigned
        -> p = br_port_get_rcu(dev);
        ....
                                                                    -> rcu_assign_pointer(dev->rx_handler_data, rx_handler_data);
                                                                     ...

Fix it in br_get_link_af_size_filtered, using br_port_get_check_rcu() and checking the return value.

Signed-off-by: Zhang Zhengming <zhangzhengming@huawei.com>
Reviewed-by: Zhao Lei <zhaolei69@huawei.com>
Reviewed-by: Wang Xiaogang <wangxiaogang3@huawei.com>
Suggested-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/bridge/br_netlink.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index a0a54482aabc..8a664148f57a 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -99,8 +99,9 @@ static size_t br_get_link_af_size_filtered(const struct net_device *dev,
 
 	rcu_read_lock();
 	if (netif_is_bridge_port(dev)) {
-		p = br_port_get_rcu(dev);
-		vg = nbp_vlan_group_rcu(p);
+		p = br_port_get_check_rcu(dev);
+		if (p)
+			vg = nbp_vlan_group_rcu(p);
 	} else if (dev->priv_flags & IFF_EBRIDGE) {
 		br = netdev_priv(dev);
 		vg = br_vlan_group_rcu(br);
-- 
2.30.2

[PATCH AUTOSEL 5.4 23/23] net: stmmac: Do not enable RX FIFO overflow interrupts

[Sasha Levin]

From: Yannick Vignon <yannick.vignon@nxp.com>

[ Upstream commit 8a7cb245cf28cb3e541e0d6c8624b95d079e155b ]

The RX FIFO overflows when the system is not able to process all received
packets and they start accumulating (first in the DMA queue in memory,
then in the FIFO). An interrupt is then raised for each overflowing packet
and handled in stmmac_interrupt(). This is counter-productive, since it
brings the system (or more likely, one CPU core) to its knees to process
the FIFO overflow interrupts.

stmmac_interrupt() handles overflow interrupts by writing the rx tail ptr
into the corresponding hardware register (according to the MAC spec, this
has the effect of restarting the MAC DMA). However, without freeing any rx
descriptors, the DMA stops right away, and another overflow interrupt is
raised as the FIFO overflows again. Since the DMA is already restarted at
the end of stmmac_rx_refill() after freeing descriptors, disabling FIFO
overflow interrupts and the corresponding handling code has no side effect,
and eliminates the interrupt storm when the RX FIFO overflows.

Signed-off-by: Yannick Vignon <yannick.vignon@nxp.com>
Link: https://lore.kernel.org/r/20210506143312.20784-1-yannick.vignon@oss.nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c  |  7 +------
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 14 ++------------
 2 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
index a41ac13cc4e5..0d993f4b701c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_dma.c
@@ -211,7 +211,7 @@ static void dwmac4_dma_rx_chan_op_mode(void __iomem *ioaddr, int mode,
 				       u32 channel, int fifosz, u8 qmode)
 {
 	unsigned int rqs = fifosz / 256 - 1;
-	u32 mtl_rx_op, mtl_rx_int;
+	u32 mtl_rx_op;
 
 	mtl_rx_op = readl(ioaddr + MTL_CHAN_RX_OP_MODE(channel));
 
@@ -282,11 +282,6 @@ static void dwmac4_dma_rx_chan_op_mode(void __iomem *ioaddr, int mode,
 	}
 
 	writel(mtl_rx_op, ioaddr + MTL_CHAN_RX_OP_MODE(channel));
-
-	/* Enable MTL RX overflow */
-	mtl_rx_int = readl(ioaddr + MTL_CHAN_INT_CTRL(channel));
-	writel(mtl_rx_int | MTL_RX_OVERFLOW_INT_EN,
-	       ioaddr + MTL_CHAN_INT_CTRL(channel));
 }
 
 static void dwmac4_dma_tx_chan_op_mode(void __iomem *ioaddr, int mode,
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 8e7c60e02fa0..10d28be73f45 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3855,7 +3855,6 @@ static irqreturn_t stmmac_interrupt(int irq, void *dev_id)
 	/* To handle GMAC own interrupts */
 	if ((priv->plat->has_gmac) || xmac) {
 		int status = stmmac_host_irq_status(priv, priv->hw, &priv->xstats);
-		int mtl_status;
 
 		if (unlikely(status)) {
 			/* For LPI we need to save the tx status */
@@ -3866,17 +3865,8 @@ static irqreturn_t stmmac_interrupt(int irq, void *dev_id)
 		}
 
 		for (queue = 0; queue < queues_count; queue++) {
-			struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
-
-			mtl_status = stmmac_host_mtl_irq_status(priv, priv->hw,
-								queue);
-			if (mtl_status != -EINVAL)
-				status |= mtl_status;
-
-			if (status & CORE_IRQ_MTL_RX_OVERFLOW)
-				stmmac_set_rx_tail_ptr(priv, priv->ioaddr,
-						       rx_q->rx_tail_addr,
-						       queue);
+			status = stmmac_host_mtl_irq_status(priv, priv->hw,
+							    queue);
 		}
 
 		/* PCS link status */
-- 
2.30.2