On 5/18/22 6:50 AM, Lee Jones wrote: > On Tue, 17 May 2022, Jens Axboe wrote: > >> On 5/17/22 7:00 AM, Lee Jones wrote: >>> On Tue, 17 May 2022, Jens Axboe wrote: >>> >>>> On 5/17/22 6:36 AM, Lee Jones wrote: >>>>> On Tue, 17 May 2022, Jens Axboe wrote: >>>>> >>>>>> On 5/17/22 6:24 AM, Lee Jones wrote: >>>>>>> On Tue, 17 May 2022, Jens Axboe wrote: >>>>>>> >>>>>>>> On 5/17/22 5:41 AM, Lee Jones wrote: >>>>>>>>> Good afternoon Jens, Pavel, et al., >>>>>>>>> >>>>>>>>> Not sure if you are presently aware, but there appears to be a >>>>>>>>> use-after-free issue affecting the io_uring worker driver (fs/io-wq.c) >>>>>>>>> in Stable v5.10.y. >>>>>>>>> >>>>>>>>> The full sysbot report can be seen below [0]. >>>>>>>>> >>>>>>>>> The C-reproducer has been placed below that [1]. >>>>>>>>> >>>>>>>>> I had great success running this reproducer in an infinite loop. >>>>>>>>> >>>>>>>>> My colleague reverse-bisected the fixing commit to: >>>>>>>>> >>>>>>>>> commit fb3a1f6c745ccd896afadf6e2d6f073e871d38ba >>>>>>>>> Author: Jens Axboe <axboe@xxxxxxxxx> >>>>>>>>> Date: Fri Feb 26 09:47:20 2021 -0700 >>>>>>>>> >>>>>>>>> io-wq: have manager wait for all workers to exit >>>>>>>>> >>>>>>>>> Instead of having to wait separately on workers and manager, just have >>>>>>>>> the manager wait on the workers. We use an atomic_t for the reference >>>>>>>>> here, as we need to start at 0 and allow increment from that. Since the >>>>>>>>> number of workers is naturally capped by the allowed nr of processes, >>>>>>>>> and that uses an int, there is no risk of overflow. >>>>>>>>> >>>>>>>>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> >>>>>>>>> >>>>>>>>> fs/io-wq.c | 30 ++++++++++++++++++++++-------- >>>>>>>>> 1 file changed, 22 insertions(+), 8 deletions(-) >>>>>>>> >>>>>>>> Does this fix it: >>>>>>>> >>>>>>>> commit 886d0137f104a440d9dfa1d16efc1db06c9a2c02 >>>>>>>> Author: Jens Axboe <axboe@xxxxxxxxx> >>>>>>>> Date: Fri Mar 5 12:59:30 2021 -0700 >>>>>>>> >>>>>>>> io-wq: fix race in freeing 'wq' and worker access >>>>>>>> >>>>>>>> Looks like it didn't make it into 5.10-stable, but we can certainly >>>>>>>> rectify that. >>>>>>> >>>>>>> Thanks for your quick response Jens. >>>>>>> >>>>>>> This patch doesn't apply cleanly to v5.10.y. >>>>>> >>>>>> This is probably why it never made it into 5.10-stable :-/ >>>>> >>>>> Right. It doesn't apply at all unfortunately. >>>>> >>>>>>> I'll have a go at back-porting it. Please bear with me. >>>>>> >>>>>> Let me know if you into issues with that and I can help out. >>>>> >>>>> I think the dependency list is too big. >>>>> >>>>> Too much has changed that was never back-ported. >>>>> >>>>> Actually the list of patches pertaining to fs/io-wq.c alone isn't so >>>>> bad, I did start to back-port them all but some of the big ones have >>>>> fs/io_uring.c changes incorporated and that list is huge (256 patches >>>>> from v5.10 to the fixing patch mentioned above). >>>> >>>> The problem is that 5.12 went to the new worker setup, and this patch >>>> landed after that even though it also applies to the pre-native workers. >>>> Hence the dependency chain isn't really as long as it seems, probably >>>> just a few patches backporting the change references and completions. >>>> >>>> I'll take a look this afternoon. >>> >>> Thanks Jens. I really appreciate it. >> >> Can you see if this helps? Untested... > > What base does this apply against please? > > I tried Mainline and v5.10.116 and both failed. It's against 5.10.116, so that's puzzling. Let me double check I sent the right one... -- Jens Axboe
