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SubjectRe: possible deadlock in process_measurement
On Thu, Jul 11, 2019 at 12:50:13PM -0700, Eric Biggers wrote:
> Hi Mimi,
>
> On Thu, Jul 11, 2019 at 10:14:36AM -0400, Mimi Zohar wrote:
> > Hi Eric,
> >
> > On Mon, 2019-06-03 at 09:35 -0700, syzbot wrote:
> > > syzbot has found a reproducer for the following crash on:
> > >
> > > HEAD commit: 3c09c195 Add linux-next specific files for 20190531
> > > git tree: linux-next
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=10f61a0ea00000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=6cfb24468280cd5c
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=5ab61747675a87ea359d
> > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=177c3d16a00000
> > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14ec01baa00000
> > >
> >
> > This reproducer seems like it is similar, but the cause is different
> > than the original report.  One has to do with overlayfs, while the
> > other has to do with ext4, mprotect/mmap.  I assume in both cases an
> > IMA policy was required to trigger the locking bug.  What type of IMA
> > policy are you using?
> >
> > Do we need to differentiate the two reports?  Is the "last occurred"
> > notification for the overlay, for mprotect, or both?  Please Cc the
> > overlay mailing list on the overlay aspect.
>
> AFAICS, syzbot boots all kernels with "ima_policy=tcb" on the command line.
> And I don't think anything in userspace changes the IMA policy.
>
> It's not unusual for multiple underlying bugs to get mixed into the same syzbot
> bug. syzbot doesn't know that one "possible deadlock in process_measurement" is
> different from another. "Last occurred" is for any crash that appeared as such.
>
> This just needs to be handled the best we can. Sometimes all the bugs can be
> fixed; sometimes they've already been fixed; or sometimes it's easiest to fix
> just one and then mark the syzbot bug as fixed, and syzbot will report it again
> it's still occurring for some other reason.
>
> - Eric

Invalidating this bug report as per the discussion at
https://lkml.kernel.org/linux-integrity/1563122888.4539.119.camel@linux.ibm.com/T/#mcd083826e5843f048c914c56a4e82147fc211704

#syz invalid

For future reference, anyone can update the status of syzbot bugs; no need to
ask me to do it. See https://goo.gl/tpsmEJ#status

- Eric

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