Syzbot reported use-after-free Read in ath9k_hif_usb_rx_cb() [0]. The
problem was in incorrect htc_handle->drv_priv initialization.
Probable call trace which can trigger use-after-free:
ath9k_htc_probe_device()
/* htc_handle->drv_priv = priv; */
ath9k_htc_wait_for_target() <--- Failed
ieee80211_free_hw() <--- priv pointer is freed
<IRQ>
...
ath9k_hif_usb_rx_cb()
ath9k_hif_usb_rx_stream()
RX_STAT_INC() <--- htc_handle->drv_priv access
In order to not add fancy protection for drv_priv we can move
htc_handle->drv_priv initialization at the end of the
ath9k_htc_probe_device() and add helper macro to make
all *_STAT_* macros NULL safe, since syzbot has reported related NULL
deref in that macros [1]
Link: https://syzkaller.appspot.com/bug?id=6ead44e37afb6866ac0c7dd121b4ce07cb665f60 [0]
Link: https://syzkaller.appspot.com/bug?id=b8101ffcec107c0567a0cd8acbbacec91e9ee8de [1]
Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Reported-and-tested-by: [email protected]
Reported-and-tested-by: [email protected]
Signed-off-by: Pavel Skripkin <[email protected]>
---
Changes since v5:
- No changes
Changes since v4:
s/save/safe/ in commit message
Changes since v3:
- s/SAVE/SAFE/
- Added links to syzkaller reports
Changes since v2:
- My send-email script forgot, that mailing lists exist.
Added back all related lists
Changes since v1:
- Removed clean-ups and moved them to 2/2
---
drivers/net/wireless/ath/ath9k/htc.h | 10 +++++-----
drivers/net/wireless/ath/ath9k/htc_drv_init.c | 3 ++-
2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index 6b45e63fa..e3d546ef7 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -327,11 +327,11 @@ static inline struct ath9k_htc_tx_ctl *HTC_SKB_CB(struct sk_buff *skb)
}
#ifdef CONFIG_ATH9K_HTC_DEBUGFS
-
-#define TX_STAT_INC(c) (hif_dev->htc_handle->drv_priv->debug.tx_stats.c++)
-#define TX_STAT_ADD(c, a) (hif_dev->htc_handle->drv_priv->debug.tx_stats.c += a)
-#define RX_STAT_INC(c) (hif_dev->htc_handle->drv_priv->debug.skbrx_stats.c++)
-#define RX_STAT_ADD(c, a) (hif_dev->htc_handle->drv_priv->debug.skbrx_stats.c += a)
+#define __STAT_SAFE(expr) (hif_dev->htc_handle->drv_priv ? (expr) : 0)
+#define TX_STAT_INC(c) __STAT_SAFE(hif_dev->htc_handle->drv_priv->debug.tx_stats.c++)
+#define TX_STAT_ADD(c, a) __STAT_SAFE(hif_dev->htc_handle->drv_priv->debug.tx_stats.c += a)
+#define RX_STAT_INC(c) __STAT_SAFE(hif_dev->htc_handle->drv_priv->debug.skbrx_stats.c++)
+#define RX_STAT_ADD(c, a) __STAT_SAFE(hif_dev->htc_handle->drv_priv->debug.skbrx_stats.c += a)
#define CAB_STAT_INC priv->debug.tx_stats.cab_queued++
#define TX_QSTAT_INC(q) (priv->debug.tx_stats.queue_stats[q]++)
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_init.c b/drivers/net/wireless/ath/ath9k/htc_drv_init.c
index ff61ae34e..07ac88fb1 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_init.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_init.c
@@ -944,7 +944,6 @@ int ath9k_htc_probe_device(struct htc_target *htc_handle, struct device *dev,
priv->hw = hw;
priv->htc = htc_handle;
priv->dev = dev;
- htc_handle->drv_priv = priv;
SET_IEEE80211_DEV(hw, priv->dev);
ret = ath9k_htc_wait_for_target(priv);
@@ -965,6 +964,8 @@ int ath9k_htc_probe_device(struct htc_target *htc_handle, struct device *dev,
if (ret)
goto err_init;
+ htc_handle->drv_priv = priv;
+
return 0;
err_init:
--
2.36.1