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SubjectRe: general protection fault in perf_misc_flags
On Mon, Sep 28, 2020 at 10:23:53PM +0200, Borislav Petkov wrote:
> 2020/09/28 22:21:01 VMs 3, executed 179, corpus cover 11792, corpus signal 10881, max signal 19337, crashes 0, repro 0

Ok, so far triggered two things:

WARNING in f2fs_is_valid_blkaddr 1 2020/09/29 10:27 reproducing
WARNING in reiserfs_put_super 1 2020/09/28 22:42

you've probably seen them already.

Anyway, next question. Let's say I trigger the corruption: is there a
way to stop the guest VM which has triggered it so that I'm able to
examine it with gdb?

What about kdump? Can I dump the guest memory either with kdump or
through the qemu monitor (I believe there's a command to dump memory) so
that it can be poked at?

Because as it is, we don't have a reproducer and as I see it, the fuzzing simply
gets restarted:

2020/09/29 10:27:03 vm-3: crash: WARNING in f2fs_is_valid_blkaddr
2020/09/29 10:27:05 loop: phase=1 shutdown=false instances=1/4 [3] repro: pending=0 reproducing=1 queued=1
2020/09/29 10:27:05 loop: starting instance 3

so it would be good to be able to say, when a vm encounters a crash, it
should be stopped immediately so that the guest can be examined through
qemu's gdb interface, i.e.,

-gdb tcp::<portnum>

or so?



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