[Crash-utility] [PATCH 1/2] Revert "Fix segfault in arm64_is_kernel_exception_frame() when corrupt stack pointer address is given"

[lijiang]

On Mon, Jun 12, 2023 at 7:24 PM Daisuke Hatayama (Fujitsu) <
d.hatayama at fujitsu.com> wrote:

> > Thank you for pointing out this issue, HATAYAMA.
> >
> > Anyway, I did not reproduce the above issue. Seems it can not always be
> reproduced.
> >
> > # ./crash /home/vmlinux
> /var/crash/127.0.0.1-2023-06-09-05\:20\:38/vmcore -s
> > WARNING: cpu 2: invalid NT_PRSTATUS note (n_type != NT_PRSTATUS)
> > WARNING: cpu 1: cannot find NT_PRSTATUS note
> > WARNING: cpu 2: cannot find NT_PRSTATUS note
> > crash> ps insmod
> >       PID    PPID  CPU       TASK        ST  %MEM      VSZ      RSS  COMM
> >      1684    1683   0  ffff06738f1cdd00  ZO   0.0        0        0
> insmod
> > crash> bt 1684
> > PID: 1684     TASK: ffff06738f1cdd00  CPU: 0    COMMAND: "insmod"
> > (no stack)
> > crash>
>
> The problematic case is the active tasks running in user mode at the
> moment of kernel panic. In most cases, it's enough to prepare some
> programs that running in infinite loop just like:
>
>     # while : ; do continue ; done &
>     [3] 3295
>
> Just in case, note that this issue is different from the one of
> corrupt mapping of NT_PRSTATUS notes. You don't need to use the
>

Thank you for the explanation,  HATAYAMA. It's true, they are different
issues, that is why it can not always be reproduced.
crash> ps insmod
      PID    PPID  CPU       TASK        ST  %MEM      VSZ      RSS  COMM
     1696    1695   2  ffff2e420cf5a900  RU   0.0     7168     3840  insmod
crash> bt 1696
PID: 1696     TASK: ffff2e420cf5a900  CPU: 2    COMMAND: "insmod"
 #0 [ffff800013eefae0] __switch_to at ffffc029d3cc9d24
 #1 [ffff800013eefb10] __schedule at ffffc029d475c1fc
 #2 [ffff800013eefba0] preempt_schedule_common at ffffc029d475cd7c
 #3 [ffff800013eefbb0] _cond_resched at ffffc029d475cdc8
 #4 [ffff800013eefbc0] down_read at ffffc029d475fdbc
 #5 [ffff800013eefbe0] blocking_notifier_call_chain at ffffc029d3d66024
 #6 [ffff800013eefc10] do_init_module at ffffc029d3e1040c
 #7 [ffff800013eefc40] load_module at ffffc029d3e12948
 #8 [ffff800013eefda0] __se_sys_finit_module at ffffc029d3e12ebc
 #9 [ffff800013eefe60] __arm64_sys_finit_module at ffffc029d3e12f7c
#10 [ffff800013eefe80] do_el0_svc at ffffc029d3cd9300
#11 [ffff800013eefeb0] el0_sync_handler at ffffc029d3cc9374
#12 [ffff800013eefff0] el0_sync at ffffc029d3cc2b7c
     PC: 0000ffff9b7637e4   LR: 0000aaaabe6b3e48   SP: 0000ffffc6f33810
    X29: 0000ffffc6f33810  X28: 0000000000000000  X27: 0000000000000000
    X26: 0000000000000002  X25: 0000000000000000  X24: 0000ffffc6f338e8
    X23: 0000aaaad7da1840  X22: 0000000000000000  X21: 0000000000000000
    X20: 0000aaaabe6bd520  X19: 0000aaaad7da1860  X18: 0000000000000000
    X17: 0000ffff9b7637c0  X16: 0000aaaabe6dfd98  X15: 0000000000000070
    X14: 0000000000000002  X13: 000000000000270f  X12: 0000000000000000
    X11: 0000000000000000  X10: 0000000000000000   X9: 0000aaaad7da1960
     X8: 0000000000000111   X7: 0000000000000001   X6: 0000000000000001
     X5: 0000000000000db1   X4: 0000000000000000   X3: 0000000000000003
     X2: 0000000000000000   X1: 0000aaaabe6bd520   X0: 0000000000000003
    ORIG_X0: 0000000000000003  SYSCALLNO: 111  PSTATE: 40001000

reproduction steps I shared. It's enough to prepare the above busy
> loop process in advance, make the kernel panic and then use bt command
> for the busy loop process.
>

You are right. I have reproduced the current problem with an infinite loop
process.

 crash> ps t
      PID    PPID  CPU       TASK        ST  %MEM      VSZ      RSS  COMM
>    8419    1896   2  ffff08aa9360ff00  RU   0.0     2432     1216  t
crash> bt 8419
PID: 8419     TASK: ffff08aa9360ff00  CPU: 2    COMMAND: "t"
bt: invalid stack pointer is given

I have no other issues about it.

Thanks.
Lianbo


> Thanks.
> HATAYAMA, Daisuke
>
>
>
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