From: Pavel Skripkin paskripkin@gmail.com

commit 0ac4827f78c7ffe8eef074bc010e7e34bc22f533 upstream.

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=6ead44e37afb6866ac0c7dd121b4ce07cb665f6... [0] Link: https://syzkaller.appspot.com/bug?id=b8101ffcec107c0567a0cd8acbbacec91e9ee8d... [1] Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.") Reported-and-tested-by: syzbot+03110230a11411024147@syzkaller.appspotmail.com Reported-and-tested-by: syzbot+c6dde1f690b60e0b9fbe@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin paskripkin@gmail.com Acked-by: Toke Høiland-Jørgensen toke@toke.dk Signed-off-by: Kalle Valo quic_kvalo@quicinc.com Link: https://lore.kernel.org/r/d57bbedc857950659bfacac0ab48790c1eda00c8.165514574... Signed-off-by: Dragos-Marian Panait dragos.panait@windriver.com --- 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 9f64e32381f9..81107100e368 100644 --- a/drivers/net/wireless/ath/ath9k/htc.h +++ b/drivers/net/wireless/ath/ath9k/htc.h @@ -325,11 +325,11 @@ 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 11054c17a9b5..eaaafa64a3ee 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: