Re: [syzbot] [kernel?] BUG: unable to handle kernel NULL pointer dereference in __hrtimer_run_queues

[Hillf Danton]

On Mon, 03 Jun 2024 03:22:29 -0700
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000090
> CPU: 0 PID: 3192 Comm: syz-executor607 Not tainted 6.10.0-rc1-syzkaller-00027-g4a4be1ad3a6e #0
> Hardware name: linux,dummy-virt (DT)
> pstate: 204000c9 (nzCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : rb_next+0x1c/0x54 lib/rbtree.c:505
> lr : rb_erase_cached include/linux/rbtree.h:124 [inline]
> lr : timerqueue_del+0x38/0x70 lib/timerqueue.c:57
> sp : ffff800080003e70
> x29: ffff800080003e70 x28: 0000000000000000 x27: fff000007f8cf780
> x26: 0000000000000001 x25: 00000000000000c0 x24: 0000001f0198bc90
> x23: fff000007f8cf780 x22: fff000007f8cf7e0 x21: fff000007f8cf780
> x20: fff000007f8cf7e0 x19: ffff800088c3bd60 x18: 0000000000000000
> x17: fff07ffffd319000 x16: ffff800080000000 x15: 0000ffffef309d38
> x14: 00000000000003bb x13: 0000000000000000 x12: ffff8000825e0028
> x11: 0000000000000001 x10: 0000000000000200 x9 : 0000000000200000
> x8 : 0008000000000000 x7 : ff7ffffffffffbff x6 : 00000000019a23f5
> x5 : fff07ffffd319000 x4 : 000000000a2dca90 x3 : ffff800088c3bd60
> x2 : ff7000007f8cf8e8 x1 : 0000000000000080 x0 : 0000000000000080
> Call trace:
>  rb_next+0x1c/0x54 lib/rbtree.c:505
>  __remove_hrtimer kernel/time/hrtimer.c:1118 [inline]
>  __run_hrtimer kernel/time/hrtimer.c:1667 [inline]
>  __hrtimer_run_queues+0x104/0x1bc kernel/time/hrtimer.c:1751
>  hrtimer_interrupt+0xe8/0x244 kernel/time/hrtimer.c:1813

After scratching head skin 30 minutes I failed to work out how the timer
was armed.