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Date: Mon, 18 May 2015 16:29:08 +0100
From: Shradha Shah <sshah@...arflare.com>
To: David Miller <davem@...emloft.net>
CC: <netdev@...r.kernel.org>, <linux-net-drivers@...arflare.com>
Subject: [PATCH net-next 07/16] sfc: protect filter table against use-after-free
From: Edward Cree <ecree@...arflare.com>
If MCDI timeouts are encountered during efx_ef10_filter_table_remove(),
an FLR will be queued, but efx->filter_state will still be kfree()d.
The queued FLR will then call efx_ef10_filter_table_restore(), which
will try to use efx->filter_state. This previously caused a panic.
This patch adds an rwsem to protect the existence of efx->filter_state,
separately from the spinlock protecting its contents. Users which can
race against efx_ef10_filter_table_remove() should down_read this rwsem.
Signed-off-by: Shradha Shah <sshah@...arflare.com>
---
drivers/net/ethernet/sfc/ef10.c | 19 +++++++++++++++++
drivers/net/ethernet/sfc/efx.c | 39 ++++++++++++++++++++++++++---------
drivers/net/ethernet/sfc/efx.h | 2 ++
drivers/net/ethernet/sfc/ethtool.c | 2 +-
drivers/net/ethernet/sfc/net_driver.h | 5 ++++-
5 files changed, 55 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 78d3236..9e2e8e1 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -3314,6 +3314,9 @@ fail:
return rc;
}
+/* Caller must hold efx->filter_sem for read if race against
+ * efx_ef10_filter_table_remove() is possible
+ */
static void efx_ef10_filter_table_restore(struct efx_nic *efx)
{
struct efx_ef10_filter_table *table = efx->filter_state;
@@ -3323,9 +3326,14 @@ static void efx_ef10_filter_table_restore(struct efx_nic *efx)
bool failed = false;
int rc;
+ WARN_ON(!rwsem_is_locked(&efx->filter_sem));
+
if (!nic_data->must_restore_filters)
return;
+ if (!table)
+ return;
+
spin_lock_bh(&efx->filter_lock);
for (filter_idx = 0; filter_idx < HUNT_FILTER_TBL_ROWS; filter_idx++) {
@@ -3361,6 +3369,7 @@ static void efx_ef10_filter_table_restore(struct efx_nic *efx)
nic_data->must_restore_filters = false;
}
+/* Caller must hold efx->filter_sem for write */
static void efx_ef10_filter_table_remove(struct efx_nic *efx)
{
struct efx_ef10_filter_table *table = efx->filter_state;
@@ -3369,6 +3378,10 @@ static void efx_ef10_filter_table_remove(struct efx_nic *efx)
unsigned int filter_idx;
int rc;
+ efx->filter_state = NULL;
+ if (!table)
+ return;
+
for (filter_idx = 0; filter_idx < HUNT_FILTER_TBL_ROWS; filter_idx++) {
spec = efx_ef10_filter_entry_spec(table, filter_idx);
if (!spec)
@@ -3394,6 +3407,9 @@ static void efx_ef10_filter_table_remove(struct efx_nic *efx)
kfree(table);
}
+/* Caller must hold efx->filter_sem for read if race against
+ * efx_ef10_filter_table_remove() is possible
+ */
static void efx_ef10_filter_sync_rx_mode(struct efx_nic *efx)
{
struct efx_ef10_filter_table *table = efx->filter_state;
@@ -3408,6 +3424,9 @@ static void efx_ef10_filter_sync_rx_mode(struct efx_nic *efx)
if (!efx_dev_registered(efx))
return;
+ if (!table)
+ return;
+
/* Mark old filters that may need to be removed */
spin_lock_bh(&efx->filter_lock);
n = table->dev_uc_count < 0 ? 1 : table->dev_uc_count;
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 864c337..50816cd 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -949,6 +949,16 @@ void efx_link_set_wanted_fc(struct efx_nic *efx, u8 wanted_fc)
static void efx_fini_port(struct efx_nic *efx);
+/* We assume that efx->type->reconfigure_mac will always try to sync RX
+ * filters and therefore needs to read-lock the filter table against freeing
+ */
+void efx_mac_reconfigure(struct efx_nic *efx)
+{
+ down_read(&efx->filter_sem);
+ efx->type->reconfigure_mac(efx);
+ up_read(&efx->filter_sem);
+}
+
/* Push loopback/power/transmit disable settings to the PHY, and reconfigure
* the MAC appropriately. All other PHY configuration changes are pushed
* through phy_op->set_settings(), and pushed asynchronously to the MAC
@@ -1002,7 +1012,7 @@ static void efx_mac_work(struct work_struct *data)
mutex_lock(&efx->mac_lock);
if (efx->port_enabled)
- efx->type->reconfigure_mac(efx);
+ efx_mac_reconfigure(efx);
mutex_unlock(&efx->mac_lock);
}
@@ -1042,7 +1052,7 @@ static int efx_init_port(struct efx_nic *efx)
/* Reconfigure the MAC before creating dma queues (required for
* Falcon/A1 where RX_INGR_EN/TX_DRAIN_EN isn't supported) */
- efx->type->reconfigure_mac(efx);
+ efx_mac_reconfigure(efx);
/* Ensure the PHY advertises the correct flow control settings */
rc = efx->phy_op->reconfigure(efx);
@@ -1068,7 +1078,7 @@ static void efx_start_port(struct efx_nic *efx)
efx->port_enabled = true;
/* Ensure MAC ingress/egress is enabled */
- efx->type->reconfigure_mac(efx);
+ efx_mac_reconfigure(efx);
mutex_unlock(&efx->mac_lock);
}
@@ -1672,10 +1682,11 @@ static int efx_probe_filters(struct efx_nic *efx)
int rc;
spin_lock_init(&efx->filter_lock);
-
+ init_rwsem(&efx->filter_sem);
+ down_write(&efx->filter_sem);
rc = efx->type->filter_table_probe(efx);
if (rc)
- return rc;
+ goto out_unlock;
#ifdef CONFIG_RFS_ACCEL
if (efx->type->offload_features & NETIF_F_NTUPLE) {
@@ -1684,12 +1695,14 @@ static int efx_probe_filters(struct efx_nic *efx)
GFP_KERNEL);
if (!efx->rps_flow_id) {
efx->type->filter_table_remove(efx);
- return -ENOMEM;
+ rc = -ENOMEM;
+ goto out_unlock;
}
}
#endif
-
- return 0;
+out_unlock:
+ up_write(&efx->filter_sem);
+ return rc;
}
static void efx_remove_filters(struct efx_nic *efx)
@@ -1697,12 +1710,16 @@ static void efx_remove_filters(struct efx_nic *efx)
#ifdef CONFIG_RFS_ACCEL
kfree(efx->rps_flow_id);
#endif
+ down_write(&efx->filter_sem);
efx->type->filter_table_remove(efx);
+ up_write(&efx->filter_sem);
}
static void efx_restore_filters(struct efx_nic *efx)
{
+ down_read(&efx->filter_sem);
efx->type->filter_table_restore(efx);
+ up_read(&efx->filter_sem);
}
/**************************************************************************
@@ -2183,7 +2200,7 @@ static int efx_change_mtu(struct net_device *net_dev, int new_mtu)
mutex_lock(&efx->mac_lock);
net_dev->mtu = new_mtu;
- efx->type->reconfigure_mac(efx);
+ efx_mac_reconfigure(efx);
mutex_unlock(&efx->mac_lock);
efx_start_all(efx);
@@ -2219,7 +2236,7 @@ static int efx_set_mac_address(struct net_device *net_dev, void *data)
/* Reconfigure the MAC */
mutex_lock(&efx->mac_lock);
- efx->type->reconfigure_mac(efx);
+ efx_mac_reconfigure(efx);
mutex_unlock(&efx->mac_lock);
return 0;
@@ -2464,7 +2481,9 @@ int efx_reset_up(struct efx_nic *efx, enum reset_type method, bool ok)
" VFs may not function\n", rc);
#endif
+ down_read(&efx->filter_sem);
efx_restore_filters(efx);
+ up_read(&efx->filter_sem);
if (efx->type->sriov_reset)
efx->type->sriov_reset(efx);
diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
index 9097906..46aee41 100644
--- a/drivers/net/ethernet/sfc/efx.h
+++ b/drivers/net/ethernet/sfc/efx.h
@@ -74,6 +74,8 @@ void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue);
/* Filters */
+void efx_mac_reconfigure(struct efx_nic *efx);
+
/**
* efx_filter_insert_filter - add or replace a filter
* @efx: NIC in which to insert the filter
diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
index 03829b4..0347976 100644
--- a/drivers/net/ethernet/sfc/ethtool.c
+++ b/drivers/net/ethernet/sfc/ethtool.c
@@ -734,7 +734,7 @@ static int efx_ethtool_set_pauseparam(struct net_device *net_dev,
/* Reconfigure the MAC. The PHY *may* generate a link state change event
* if the user just changed the advertised capabilities, but there's no
* harm doing this twice */
- efx->type->reconfigure_mac(efx);
+ efx_mac_reconfigure(efx);
out:
mutex_unlock(&efx->mac_lock);
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 55a5f48..f6c4832 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -25,6 +25,7 @@
#include <linux/highmem.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
+#include <linux/rwsem.h>
#include <linux/vmalloc.h>
#include <linux/i2c.h>
#include <linux/mtd/mtd.h>
@@ -896,7 +897,8 @@ struct vfdi_status;
* @loopback_mode: Loopback status
* @loopback_modes: Supported loopback mode bitmask
* @loopback_selftest: Offline self-test private state
- * @filter_lock: Filter table lock
+ * @filter_sem: Filter table rw_semaphore, for freeing the table
+ * @filter_lock: Filter table lock, for mere content changes
* @filter_state: Architecture-dependent filter table state
* @rps_flow_id: Flow IDs of filters allocated for accelerated RFS,
* indexed by filter ID
@@ -1038,6 +1040,7 @@ struct efx_nic {
void *loopback_selftest;
+ struct rw_semaphore filter_sem;
spinlock_t filter_lock;
void *filter_state;
#ifdef CONFIG_RFS_ACCEL
--
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