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 >>>>>>>>>>> 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 >>>>>>>>>>> >>>>>>>>>>> fs/io-wq.c | 30 ++++++++++++++++++++++-------- >>>>>>>>>>> 1 file changed, 22 insertions(+), 8 deletions(-) >>>>>>>>>> >>>>>>>>>> Does this fix it: >>>>>>>>>> >>>>>>>>>> commit 886d0137f104a440d9dfa1d16efc1db06c9a2c02 >>>>>>>>>> Author: Jens Axboe >>>>>>>>>> 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. -- Jens Axboe