Hi Toke, On 5/12/22 15:49, Toke Høiland-Jørgensen wrote:
Pavel Skripkin <paskripkin@xxxxxxxxx> writes:Syzbot reported use-after-free Read in ath9k_hif_usb_rx_cb(). 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 save. 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>Could you link the original syzbot report in the commit message as well,
Sure! See links below use-after-free bug: https://syzkaller.appspot.com/bug?id=6ead44e37afb6866ac0c7dd121b4ce07cb665f60 NULL deref bug: https://syzkaller.appspot.com/bug?id=b8101ffcec107c0567a0cd8acbbacec91e9ee8de I can add them in commit message if you want :)
please? Also that 'tested-by' implies that syzbot run-tested this? How does it do that; does it have ath9k_htc hardware?
No, it uses CONFIG_USB_RAW_GADGET and CONFIG_USB_DUMMY_HCD for gadgets for emulating usb devices.
Basically these things "connect" fake USB device with random usb ids from hardcoded table and try to do various things with usb driver
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-#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_SAVE(expr) (hif_dev->htc_handle->drv_priv ? (expr) : 0) +#define TX_STAT_INC(c) __STAT_SAVE(hif_dev->htc_handle->drv_priv->debug.tx_stats.c++) +#define TX_STAT_ADD(c, a) __STAT_SAVE(hif_dev->htc_handle->drv_priv->debug.tx_stats.c += a) +#define RX_STAT_INC(c) __STAT_SAVE(hif_dev->htc_handle->drv_priv->debug.skbrx_stats.c++) +#define RX_STAT_ADD(c, a) __STAT_SAVE(hif_dev->htc_handle->drv_priv->debug.skbrx_stats.c += a) #define CAB_STAT_INC priv->debug.tx_stats.cab_queued++s/SAVE/SAFE/ here and in the next patch (and the commit message).
Oh, sorry about that! Will update in next version With regards, Pavel Skripkin
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