Re: [syzbot] [mm?] kernel panic: corrupted stack end in userfaultfd_ioctl

[Lance Yang]

On Wed, Jun 5, 2024 at 11:23 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
>
> For some reason this thread doesn't appear in my linux-mm archive.
> Lance, please take a look?

Hi Andrew, thanks for pointing this out!

Hi Hillf, thanks a lot for helping to test the patch[1] with syzbot!

I noticed that syzbot has confirmed the patch and that the reproducer
did not trigger any issues[2].

Hopefully, the patch[3] will land in -rc3 to make the testing bots happy.

[1] https://lore.kernel.org/all/20240604123656.1730-1-hdanton@xxxxxxxx/
[2] https://lore.kernel.org/all/000000000000a3bf64061a101538@xxxxxxxxxx/
[3] https://lore.kernel.org/linux-mm/20240524005444.135417-1-21cnbao@xxxxxxxxx/

Thanks,
Lance


>
>
> On Mon, 03 Jun 2024 06:05:33 -0700 syzbot <syzbot+5a1cb2c00e895afca87e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    4a4be1ad3a6e Revert "vfs: Delete the associated dentry whe..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=104284f2980000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=bd6024aedb15e15c
> > dashboard link: https://syzkaller.appspot.com/bug?extid=5a1cb2c00e895afca87e
> > compiler:       aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> > userspace arch: arm64
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=124e1664980000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15683162980000
> >
> > Downloadable assets:
> > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/384ffdcca292/non_bootable_disk-4a4be1ad.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/75957361122b/vmlinux-4a4be1ad.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/6c766b0ec377/Image-4a4be1ad.gz.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+5a1cb2c00e895afca87e@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > Kernel panic - not syncing: corrupted stack end detected inside scheduler
> > CPU: 1 PID: 3188 Comm: syz-executor396 Not tainted 6.10.0-rc1-syzkaller-00027-g4a4be1ad3a6e #0
> > Hardware name: linux,dummy-virt (DT)
> > Call trace:
> >  dump_backtrace+0x94/0xec arch/arm64/kernel/stacktrace.c:317
> >  show_stack+0x18/0x24 arch/arm64/kernel/stacktrace.c:324
> >  __dump_stack lib/dump_stack.c:88 [inline]
> >  dump_stack_lvl+0x38/0x90 lib/dump_stack.c:114
> >  dump_stack+0x18/0x24 lib/dump_stack.c:123
> >  panic+0x39c/0x3d0 kernel/panic.c:347
> >  schedule_debug kernel/sched/core.c:5962 [inline]
> >  schedule+0x0/0x104 kernel/sched/core.c:6628
> >  preempt_schedule_irq+0x3c/0x80 kernel/sched/core.c:7067
> >  arm64_preempt_schedule_irq arch/arm64/kernel/entry-common.c:301 [inline]
> >  __el1_irq arch/arm64/kernel/entry-common.c:539 [inline]
> >  el1_interrupt+0x4c/0x64 arch/arm64/kernel/entry-common.c:551
> >  el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:556
> >  el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:594
> >  __rcu_read_lock+0x0/0x14 kernel/rcu/tree_stall.h:125
> >  pte_offset_map_nolock+0x38/0xb0 mm/pgtable-generic.c:314
> >  move_pages_pte mm/userfaultfd.c:1160 [inline]
> >  move_pages+0x330/0x13a4 mm/userfaultfd.c:1733
> >  userfaultfd_move fs/userfaultfd.c:2016 [inline]
> >  userfaultfd_ioctl+0x6f4/0x1ed8 fs/userfaultfd.c:2134
> >  vfs_ioctl fs/ioctl.c:51 [inline]
> >  __do_sys_ioctl fs/ioctl.c:907 [inline]
> >  __se_sys_ioctl fs/ioctl.c:893 [inline]
> >  __arm64_sys_ioctl+0xac/0xf0 fs/ioctl.c:893
> >  __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
> >  invoke_syscall+0x48/0x118 arch/arm64/kernel/syscall.c:48
> >  el0_svc_common.constprop.0+0x40/0xe0 arch/arm64/kernel/syscall.c:133
> >  do_el0_svc+0x1c/0x28 arch/arm64/kernel/syscall.c:152
> >  el0_svc+0x34/0xf8 arch/arm64/kernel/entry-common.c:712
> >  el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730
> >  el0t_64_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:598
> > SMP: stopping secondary CPUs
> > Kernel Offset: disabled
> > CPU features: 0x00,00000006,8f17bd7c,1767f6bf
> > Memory Limit: none
> > Rebooting in 86400 seconds..
> >
> >
> > ---
> > This report is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
> >
> > syzbot will keep track of this issue. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> >
> > If the report is already addressed, let syzbot know by replying with:
> > #syz fix: exact-commit-title
> >
> > If you want syzbot to run the reproducer, reply with:
> > #syz test: git://repo/address.git branch-or-commit-hash
> > If you attach or paste a git patch, syzbot will apply it before testing.
> >
> > If you want to overwrite report's subsystems, reply with:
> > #syz set subsystems: new-subsystem
> > (See the list of subsystem names on the web dashboard)
> >
> > If the report is a duplicate of another one, reply with:
> > #syz dup: exact-subject-of-another-report
> >
> > If you want to undo deduplication, reply with:
> > #syz undup