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Subject[PATCH v2] staging: rtl8192u: Fix sleep in atomic context bug in dm_fsync_timer_callback
Date
There are sleep in atomic context bugs when dm_fsync_timer_callback is
executing. The root cause is that the memory allocation functions with
GFP_KERNEL or GFP_NOIO parameters are called in dm_fsync_timer_callback
which is a timer handler. The call paths that could trigger bugs are
shown below:

(interrupt context)
dm_fsync_timer_callback
write_nic_byte
kzalloc(sizeof(data), GFP_KERNEL); //may sleep
usb_control_msg
kmalloc(.., GFP_NOIO); //may sleep
write_nic_dword
kzalloc(sizeof(data), GFP_KERNEL); //may sleep
usb_control_msg
kmalloc(.., GFP_NOIO); //may sleep

This patch uses delayed work to replace timer and moves the operations
that may sleep into the delayed work in order to mitigate bugs.

Fixes: 8fc8598e61f6 ("Staging: Added Realtek rtl8192u driver to staging")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
Changes in v2:
- Use delayed work to replace timer.

drivers/staging/rtl8192u/r8192U.h | 2 +-
drivers/staging/rtl8192u/r8192U_dm.c | 38 +++++++++++++---------------
drivers/staging/rtl8192u/r8192U_dm.h | 2 +-
3 files changed, 20 insertions(+), 22 deletions(-)

diff --git a/drivers/staging/rtl8192u/r8192U.h b/drivers/staging/rtl8192u/r8192U.h
index 14ca00a2789..1942cb84937 100644
--- a/drivers/staging/rtl8192u/r8192U.h
+++ b/drivers/staging/rtl8192u/r8192U.h
@@ -1013,7 +1013,7 @@ typedef struct r8192_priv {
bool bis_any_nonbepkts;
bool bcurrent_turbo_EDCA;
bool bis_cur_rdlstate;
- struct timer_list fsync_timer;
+ struct delayed_work fsync_work;
bool bfsync_processing; /* 500ms Fsync timer is active or not */
u32 rate_record;
u32 rateCountDiffRecord;
diff --git a/drivers/staging/rtl8192u/r8192U_dm.c b/drivers/staging/rtl8192u/r8192U_dm.c
index 725bf5ca9e3..0fcfcaa6500 100644
--- a/drivers/staging/rtl8192u/r8192U_dm.c
+++ b/drivers/staging/rtl8192u/r8192U_dm.c
@@ -2578,19 +2578,20 @@ static void dm_init_fsync(struct net_device *dev)
priv->ieee80211->fsync_seconddiff_ratethreshold = 200;
priv->ieee80211->fsync_state = Default_Fsync;
priv->framesyncMonitor = 1; /* current default 0xc38 monitor on */
- timer_setup(&priv->fsync_timer, dm_fsync_timer_callback, 0);
+ INIT_DELAYED_WORK(&priv->fsync_work, dm_fsync_work_callback);
}

static void dm_deInit_fsync(struct net_device *dev)
{
struct r8192_priv *priv = ieee80211_priv(dev);

- del_timer_sync(&priv->fsync_timer);
+ cancel_delayed_work_sync(&priv->fsync_work);
}

-void dm_fsync_timer_callback(struct timer_list *t)
+void dm_fsync_work_callback(struct work_struct *work)
{
- struct r8192_priv *priv = from_timer(priv, t, fsync_timer);
+ struct r8192_priv *priv =
+ container_of(work, struct r8192_priv, fsync_work.work);
struct net_device *dev = priv->ieee80211->dev;
u32 rate_index, rate_count = 0, rate_count_diff = 0;
bool bSwitchFromCountDiff = false;
@@ -2657,17 +2658,16 @@ void dm_fsync_timer_callback(struct timer_list *t)
}
}
if (bDoubleTimeInterval) {
- if (timer_pending(&priv->fsync_timer))
- del_timer_sync(&priv->fsync_timer);
- priv->fsync_timer.expires = jiffies +
- msecs_to_jiffies(priv->ieee80211->fsync_time_interval*priv->ieee80211->fsync_multiple_timeinterval);
- add_timer(&priv->fsync_timer);
+ cancel_delayed_work_sync(&priv->fsync_work);
+ schedule_delayed_work(&priv->fsync_work,
+ msecs_to_jiffies(priv
+ ->ieee80211->fsync_time_interval *
+ priv->ieee80211->fsync_multiple_timeinterval));
} else {
- if (timer_pending(&priv->fsync_timer))
- del_timer_sync(&priv->fsync_timer);
- priv->fsync_timer.expires = jiffies +
- msecs_to_jiffies(priv->ieee80211->fsync_time_interval);
- add_timer(&priv->fsync_timer);
+ cancel_delayed_work_sync(&priv->fsync_work);
+ schedule_delayed_work(&priv->fsync_work,
+ msecs_to_jiffies(priv
+ ->ieee80211->fsync_time_interval));
}
} else {
/* Let Register return to default value; */
@@ -2695,7 +2695,7 @@ static void dm_EndSWFsync(struct net_device *dev)
struct r8192_priv *priv = ieee80211_priv(dev);

RT_TRACE(COMP_HALDM, "%s\n", __func__);
- del_timer_sync(&(priv->fsync_timer));
+ cancel_delayed_work_sync(&priv->fsync_work);

/* Let Register return to default value; */
if (priv->bswitch_fsync) {
@@ -2736,11 +2736,9 @@ static void dm_StartSWFsync(struct net_device *dev)
if (priv->ieee80211->fsync_rate_bitmap & rateBitmap)
priv->rate_record += priv->stats.received_rate_histogram[1][rateIndex];
}
- if (timer_pending(&priv->fsync_timer))
- del_timer_sync(&priv->fsync_timer);
- priv->fsync_timer.expires = jiffies +
- msecs_to_jiffies(priv->ieee80211->fsync_time_interval);
- add_timer(&priv->fsync_timer);
+ cancel_delayed_work_sync(&priv->fsync_work);
+ schedule_delayed_work(&priv->fsync_work,
+ msecs_to_jiffies(priv->ieee80211->fsync_time_interval));

write_nic_dword(dev, rOFDM0_RxDetector2, 0x465c12cd);
}
diff --git a/drivers/staging/rtl8192u/r8192U_dm.h b/drivers/staging/rtl8192u/r8192U_dm.h
index 0b2a1c68859..2159018b4e3 100644
--- a/drivers/staging/rtl8192u/r8192U_dm.h
+++ b/drivers/staging/rtl8192u/r8192U_dm.h
@@ -166,7 +166,7 @@ void dm_force_tx_fw_info(struct net_device *dev,
void dm_init_edca_turbo(struct net_device *dev);
void dm_rf_operation_test_callback(unsigned long data);
void dm_rf_pathcheck_workitemcallback(struct work_struct *work);
-void dm_fsync_timer_callback(struct timer_list *t);
+void dm_fsync_work_callback(struct work_struct *work);
void dm_cck_txpower_adjust(struct net_device *dev, bool binch14);
void dm_shadow_init(struct net_device *dev);
void dm_initialize_txpower_tracking(struct net_device *dev);
--
2.17.1
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