Re: BUG: core dump in selftest of proc fs

[Mirsad Goran Todorovac]

On 06. 01. 2023. 11:39, Alexey Dobriyan wrote:
> On Wed, Jan 04, 2023 at 07:27:40PM +0100, Mirsad Goran Todorovac wrote:
> > Dear all,
> >
> > Trying to complete `make kselftest` for the first time, so maybe I'm doing something wrong?
> >
> > Or we are having a regression in 6.2-rc2 release candidate ...
> >
> > However, the output of selftest run is:
> >
> > make[2]: Entering directory '.../linux_torvalds/tools/testing/selftests/proc'
> > TAP version 13
> > 1..21
> > # selftests: proc: fd-001-lookup
> > ok 1 selftests: proc: fd-001-lookup
> > # selftests: proc: fd-002-posix-eq
> > ok 2 selftests: proc: fd-002-posix-eq
> > # selftests: proc: fd-003-kthread
> > ok 3 selftests: proc: fd-003-kthread
> > # selftests: proc: proc-loadavg-001
> > ok 4 selftests: proc: proc-loadavg-001
> > # selftests: proc: proc-empty-vm
> > # proc-empty-vm: proc-empty-vm.c:184: test_proc_pid_maps: Assertion `rv == 0' failed.
> > # /usr/bin/timeout: the monitored command dumped core
> > # Aborted
> > not ok 5 selftests: proc: proc-empty-vm # exit=134
> > # selftests: proc: proc-pid-vm
> > # proc-pid-vm: proc-pid-vm.c:365: main: Assertion `rv == len' failed.
> > # /usr/bin/timeout: the monitored command dumped core
> > # Aborted
> >
> > Please find attached lshw output, dmesg, config and lsmod.
> >
> > I am available for further diagnostics.
> >
> > The platform is Ubuntu 22.10 kinetic kudu on a Lenovo Ideapad 3 15ITL6 laptop.
>
> The "bug" is that "call rel32" instruction testing for executable
> vsyscall page which should be relocated to "call 0xffffffffff600000"
> is messed up. Ubuntu 22.10 ships with "vsyscall=xonly" so there should not be
> any faults when executing from it. But segfault happens with normal
> randomised userspace address.
>
> I'll change it to "call *rax" which should be more robust (and works)
> and free from relocations.

If you will need to test the patch in the same environment where the problem initially
occurred, I am ready at your disposal.

Thanks,
Mirsad

--
Mirsad Goran Todorovac
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
--
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
The European Union