Pavel Skripkin <paskripkin@xxxxxxxxx> writes: > 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 :) Yes, please do! >> 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 Ah, right, hence the failures I suppose? Makes sense. > [snip] > >>> -#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 Thanks! Other than that, I think the patch looks reasonable... -Toke