Re: [PATCH] net: ath9k: fix use-after-free in ath9k_hif_usb_rx_cb

On 8/4/21 10:48 PM, Pavel Skripkin wrote:

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.

Also, I made whitespaces clean ups in *_STAT_* macros definitions
to make checkpatch.pl happy.

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Reported-and-tested-by: syzbot+03110230a11411024147@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <redacted>
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Hi, ath9k maintainer/developers!

I know, that you do not like changes, that wasn't tested on real
hardware. I really don't access to this one, so I'd like you to test it on
real hardware piece, if you have one. At least, this patch was tested by
syzbot [1]

[1] https://syzkaller.appspot.com/bug?id=6ead44e37afb6866ac0c7dd121b4ce07cb665f60

---

Btw, this patch also passes this syzbot test

https://syzkaller.appspot.com/bug?id=b8101ffcec107c0567a0cd8acbbacec91e9ee8de


With regards,
Pavel Skripkin