On Tue, 15 Mar 2022 at 18:08, Linus Torvalds
[off-list ref] wrote:

On Tue, Mar 15, 2022 at 2:36 AM syzbot
[off-list ref] wrote:

quoted

syzbot suspects this issue was fixed by commit
09688c0166e7 ("Linux 5.17-rc8")

No, I'm afraid that means that the bisection is broken:

quoted

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=140283ad700000

and yeah, looking at that log it looks like every single run has

  testing commit [...]
  run #0: crashed: KASAN: use-after-free Read in ath9k_hif_usb_rx_cb
  ...
  # git bisect good [...]

and you never saw a "bad" commit that didn't have the issue, so the
top-of-tree gets marked "good" (and I suspect you intentionally mark
the broken case "good" in order to find where it got fixed, so you're
using "git bisect" in a reverse way).

I didn't look closer, but it does seem to not reproduce very reliably,
maybe that is what confused the bot originally.

Hi Linus,

Thanks for taking a look. Yes, it's a "reverse" bisection that tries
to find the fix.
And your conclusion re flakiness looks right, there were few runs with
only 1/20 crashes.
But the bug looks to be fixed by something anyway. git log on the file
pretty clearly points to:

#syz fix: ath9k: Fix out-of-bound memcpy in ath9k_hif_usb_rx_stream