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: syzbot+03110230a11411024147@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-and-tested-by: syzbot+c6dde1f690b60e0b9fbe@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx> --- 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 6b45e63fae4b..e3d546ef71dd 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 ff61ae34ecdf..07ac88fb1c57 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
