On Wed, 18 May 2022, Jens Axboe wrote: > On 5/18/22 6:54 AM, Jens Axboe wrote: > > On 5/18/22 6:52 AM, Jens Axboe wrote: > >> 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... > > > > Looks like I sent the one from the wrong directory, sorry about that. > > This one should be better: > > Nope, both are the right one. Maybe your mailer is mangling the patch? > I'll attach it gzip'ed here in case that helps. Okay, that applied, thanks. Unfortunately, I am still able to crash the kernel in the same way. -- Lee Jones [李琼斯] Principal Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
