On 9/10/24 06:03, 'A. Sverdlin' via BCM-KERNEL-FEEDBACK-LIST,PDL wrote:
From: Alexander Sverdlin <[email protected]>
There are multiple races of zeroing dsa_ptr in struct net_device (on
shutdown/remove) against asynchronous dereferences all over the net
code. Widespread pattern is as follows:
CPU0 CPU1
if (netdev_uses_dsa())
dev->dsa_ptr = NULL;
dev->dsa_ptr->...
One of the possible crashes:
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000010
CPU: 0 PID: 12 Comm: ksoftirqd/0 Tainted: G O 6.1.99+ #1
pc : lan9303_rcv
lr : lan9303_rcv
Call trace:
lan9303_rcv
dsa_switch_rcv
__netif_receive_skb_list_core
netif_receive_skb_list_internal
napi_gro_receive
fec_enet_rx_napi
__napi_poll
net_rx_action
...
RCU-protect dsa_ptr and use rcu_dereference() or rtnl_dereference()
depending on the calling context.
Rename netdev_uses_dsa() into __netdev_uses_dsa_currently()
(assumes ether RCU or RTNL lock held) and netdev_uses_dsa_currently()
variants which better reflect the uselessness of the function's
return value, which becomes outdated right after the call.
Fixes: ee534378f005 ("net: dsa: fix panic when DSA master device unbinds on
shutdown")
Cc: [email protected]
Signed-off-by: Alexander Sverdlin <[email protected]>
Thanks for doing this work, just a few nits below. This is likely to be
difficult to backport to stable trees.
---
drivers/net/dsa/mt7530.c | 3 +-
drivers/net/dsa/ocelot/felix.c | 3 +-
drivers/net/dsa/qca/qca8k-8xxx.c | 3 +-
drivers/net/ethernet/broadcom/bcmsysport.c | 8 +-
drivers/net/ethernet/mediatek/airoha_eth.c | 2 +-
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 22 +++--
drivers/net/ethernet/mediatek/mtk_ppe.c | 15 ++-
include/linux/netdevice.h | 2 +-
include/net/dsa.h | 36 +++++--
include/net/dsa_stubs.h | 6 +-
net/bridge/br_input.c | 2 +-
net/core/dev.c | 3 +-
net/core/flow_dissector.c | 19 ++--
net/dsa/conduit.c | 66 ++++++++-----
net/dsa/dsa.c | 19 ++--
net/dsa/port.c | 3 +-
net/dsa/tag.c | 3 +-
net/dsa/tag.h | 19 ++--
net/dsa/tag_8021q.c | 10 +-
net/dsa/tag_brcm.c | 2 +-
net/dsa/tag_dsa.c | 8 +-
net/dsa/tag_qca.c | 10 +-
net/dsa/tag_sja1105.c | 22 +++--
net/dsa/user.c | 104 +++++++++++---------
net/ethernet/eth.c | 2 +-
25 files changed, 240 insertions(+), 152 deletions(-)
diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index ec18e68bf3a8..82d3f1786156 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -20,6 +20,7 @@
#include <linux/reset.h>
#include <linux/gpio/consumer.h>
#include <linux/gpio/driver.h>
+#include <linux/rtnetlink.h>
#include <net/dsa.h>
#include "mt7530.h"
@@ -3092,7 +3093,7 @@ mt753x_conduit_state_change(struct dsa_switch *ds,
const struct net_device *conduit,
bool operational)
{
- struct dsa_port *cpu_dp = conduit->dsa_ptr;
+ struct dsa_port *cpu_dp = rtnl_dereference(conduit->dsa_ptr);
Out of curiosity, only sparse will likely be able to recognize the __rcu
annotation of net_device::dsa_ptr so there is still unfortunately room
for programmers to forget about using rtnl_dereference(), this should
hopefully be caught by CI when patches are submitted.
struct mt7530_priv *priv = ds->priv;
int val = 0;
u8 mask;
diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index 4a705f7333f4..f6bc0ff0c116 100644
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -21,6 +21,7 @@
#include <linux/of_net.h>
#include <linux/pci.h>
#include <linux/of.h>
+#include <linux/rtnetlink.h>
#include <net/pkt_sched.h>
#include <net/dsa.h>
#include "felix.h"
@@ -57,7 +58,7 @@ static int felix_cpu_port_for_conduit(struct dsa_switch *ds,
return lag;
}
- cpu_dp = conduit->dsa_ptr;
+ cpu_dp = rtnl_dereference(conduit->dsa_ptr);
return cpu_dp->index;
}
diff --git a/drivers/net/dsa/qca/qca8k-8xxx.c b/drivers/net/dsa/qca/qca8k-8xxx.c
index f8d8c70642c4..10b4d7e9be2f 100644
--- a/drivers/net/dsa/qca/qca8k-8xxx.c
+++ b/drivers/net/dsa/qca/qca8k-8xxx.c
@@ -20,6 +20,7 @@
#include <linux/gpio/consumer.h>
#include <linux/etherdevice.h>
#include <linux/dsa/tag_qca.h>
+#include <linux/rtnetlink.h>
#include "qca8k.h"
#include "qca8k_leds.h"
@@ -1754,7 +1755,7 @@ static void
qca8k_conduit_change(struct dsa_switch *ds, const struct net_device *conduit,
bool operational)
{
- struct dsa_port *dp = conduit->dsa_ptr;
+ struct dsa_port *dp = rtnl_dereference(conduit->dsa_ptr);
struct qca8k_priv *priv = ds->priv;
/* Ethernet MIB/MDIO is only supported for CPU port 0 */
diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c
b/drivers/net/ethernet/broadcom/bcmsysport.c
index c9faa8540859..bd9bc081346d 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -145,7 +145,7 @@ static void bcm_sysport_set_rx_csum(struct net_device *dev,
* sure we tell the RXCHK hardware to expect a 4-bytes Broadcom
* tag after the Ethernet MAC Source Address.
*/
- if (netdev_uses_dsa(dev))
+ if (__netdev_uses_dsa_currently(dev))
I appreciate the thought given into the function name, though I am not
sure it is warranted to suffix with _currently().
reg |= RXCHK_BRCM_TAG_EN;
else
reg &= ~RXCHK_BRCM_TAG_EN;
@@ -173,7 +173,7 @@ static void bcm_sysport_set_tx_csum(struct net_device *dev,
* checksum to be computed correctly when using VLAN HW acceleration,
* else it has no effect, so it can always be turned on.
*/
- if (netdev_uses_dsa(dev))
+ if (__netdev_uses_dsa_currently(dev))
reg |= tdma_control_bit(priv, SW_BRCM_TAG);
else
reg &= ~tdma_control_bit(priv, SW_BRCM_TAG);
@@ -1950,7 +1950,7 @@ static inline void gib_set_pad_extension(struct
bcm_sysport_priv *priv)
reg = gib_readl(priv, GIB_CONTROL);
/* Include Broadcom tag in pad extension and fix up IPG_LENGTH */
- if (netdev_uses_dsa(priv->netdev)) {
+ if (__netdev_uses_dsa_currently(priv->netdev)) {
reg &= ~(GIB_PAD_EXTENSION_MASK << GIB_PAD_EXTENSION_SHIFT);
reg |= ENET_BRCM_TAG_LEN << GIB_PAD_EXTENSION_SHIFT;
}
@@ -2299,7 +2299,7 @@ static u16 bcm_sysport_select_queue(struct net_device
*dev, struct sk_buff *skb,
struct bcm_sysport_tx_ring *tx_ring;
unsigned int q, port;
- if (!netdev_uses_dsa(dev))
+ if (!__netdev_uses_dsa_currently(dev))
return netdev_pick_tx(dev, skb, NULL);
/* DSA tagging layer will have configured the correct queue */
diff --git a/drivers/net/ethernet/mediatek/airoha_eth.c
b/drivers/net/ethernet/mediatek/airoha_eth.c
index 1c5b85a86df1..f7425d393b22 100644
--- a/drivers/net/ethernet/mediatek/airoha_eth.c
+++ b/drivers/net/ethernet/mediatek/airoha_eth.c
@@ -2255,7 +2255,7 @@ static int airoha_dev_open(struct net_device *dev)
if (err)
return err;
- if (netdev_uses_dsa(dev))
+ if (__netdev_uses_dsa_currently(dev))
airoha_fe_set(eth, REG_GDM_INGRESS_CFG(port->id),
GDM_STAG_EN_MASK);
else
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 16ca427cf4c3..82a828349323 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -24,6 +24,7 @@
#include <linux/pcs/pcs-mtk-lynxi.h>
#include <linux/jhash.h>
#include <linux/bitfield.h>
+#include <linux/rcupdate.h>
#include <net/dsa.h>
#include <net/dst_metadata.h>
#include <net/page_pool/helpers.h>
@@ -1375,7 +1376,8 @@ static void mtk_tx_set_dma_desc_v2(struct net_device
*dev, void *txd,
/* tx checksum offload */
if (info->csum)
data |= TX_DMA_CHKSUM_V2;
- if (mtk_is_netsys_v3_or_greater(eth) && netdev_uses_dsa(dev))
+ if (mtk_is_netsys_v3_or_greater(eth) &&
+ __netdev_uses_dsa_currently(dev))
data |= TX_DMA_SPTAG_V3;
}
WRITE_ONCE(desc->txd5, data);
@@ -2183,7 +2185,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int
budget,
* hardware treats the MTK special tag as a VLAN and untags it.
*/
if (mtk_is_netsys_v1(eth) && (trxd.rxd2 & RX_DMA_VTAG) &&
- netdev_uses_dsa(netdev)) {
+ __netdev_uses_dsa_currently(netdev)) {
unsigned int port = RX_DMA_VPID(trxd.rxd3) & GENMASK(2,
0);
if (port < ARRAY_SIZE(eth->dsa_meta) &&
@@ -3304,7 +3306,7 @@ static void mtk_gdm_config(struct mtk_eth *eth, u32 id,
u32 config)
val |= config;
- if (eth->netdev[id] && netdev_uses_dsa(eth->netdev[id]))
+ if (eth->netdev[id] && __netdev_uses_dsa_currently(eth->netdev[id]))
val |= MTK_GDMA_SPECIAL_TAG;
mtk_w32(eth, val, MTK_GDMA_FWD_CFG(id));
@@ -3313,12 +3315,16 @@ static void mtk_gdm_config(struct mtk_eth *eth, u32 id,
u32 config)
static bool mtk_uses_dsa(struct net_device *dev)
{
+ bool ret = false;
#if IS_ENABLED(CONFIG_NET_DSA)
- return netdev_uses_dsa(dev) &&
- dev->dsa_ptr->tag_ops->proto == DSA_TAG_PROTO_MTK;
-#else
- return false;
+ struct dsa_port *dp;
+
+ rcu_read_lock();
+ dp = rcu_dereference(dev->dsa_ptr);
+ ret = dp && dp->tag_ops->proto == DSA_TAG_PROTO_MTK;
+ rcu_read_unlock();
This pattern repeats in mtk_ppe.c, a possible factoring for later.
--
Florian
