On Fri, 15 Jan 2016 20:13:11 +0100, Dmitry Vyukov wrote:
On Fri, Jan 15, 2016 at 3:38 PM, Dmitry Vyukov dvyukov@google.com wrote:
On Fri, Jan 15, 2016 at 2:51 PM, Takashi Iwai tiwai@suse.de wrote:
On Fri, 15 Jan 2016 12:03:17 +0100, Dmitry Vyukov wrote:
On Fri, Jan 15, 2016 at 12:00 PM, Takashi Iwai tiwai@suse.de wrote:
On Fri, 15 Jan 2016 09:06:10 +0100, Dmitry Vyukov wrote:
On Thu, Jan 14, 2016 at 5:09 PM, Takashi Iwai tiwai@suse.de wrote: > On Wed, 13 Jan 2016 21:54:10 +0100, > Takashi Iwai wrote: >> >> OK, then this might be a possible race at the current snd_timer_stop() >> implementation. There is no sync action there, so the ISR might be >> still alive after snd_timer_close() call. Or might be another race. >> This pattern looks a bit different, as it's involved with hrtimer. >> >> I'll take a look at it tomorrow. > > I've audited the code today, but the open window doesn't look like > what I expected. I found only some possible cases with slave timer > instances. > > In anyway, below is a test fix patch. Since I couldn't reproduce the > issue on my local machines, it's hard to say whether this covers the > holes you fell. Let's see...
Hi Takashi,
I would be interested to understand why other people can't reproduce issues that I hit pretty reliably. I suspect that it can be due to .config. Please try with the following config values.
I guess rather other config, e.g. the kernel debug options. I suppose you enabled KASAN and DEBUG_LIST. What else?
I've attached my config (you will need to disable CONFIG_KCOV, it is not upstreamed).
Hm, that has lots of other drivers built-in...
I also start qemu with "-soundhw all" arg.
OK, so you're testing with VM? This makes easier to recheck.
Yes, I start qemu as:
qemu-system-x86_64 -hda wheezy.img -net user,host=10.0.2.10,hostfwd=tcp::10022-:22 -net nic -nographic -kernel arch/x86/boot/bzImage -append "console=ttyS0 root=/dev/sda debug earlyprintk=serial slub_debug=UZ" -enable-kvm -m 2G -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 -smp sockets=2,cores=2,threads=1 -usb -usbdevice mouse -usbdevice tablet -soundhw all
And which test did trigger use-after-free, even with all previous patches?
I will try to extract a new reproducer now.
Ok, I does not seem to see any crashes except the timer hangs below. Let's consider all other bugs as fixed. I will report anything new that I see separately.
OK, good to hear.
Meanwhile, can you try to reproduce this one: https://groups.google.com/forum/#!msg/syzkaller/bbtG9_h1ONU/CPLblMC6FAAJ ? I run the program in a tight parallel loop.
I could reproduce this after your suggestion with parallel runs.
This seems specific to hrtimer. Possibly it's not about the snd-timer core itself. Could you check whether this doesn't happen when CONFIG_SND_HRTIMER isn't set?
thanks,
Takashi