Re: [BUG] NULL pointer dereference probably caused by kernel/trace/ring_buffer.c

From: Steven Rostedt
Date: Tue Nov 01 2022 - 17:38:09 EST


On Tue, 1 Nov 2022 21:07:20 +0100
Roland Ruckerbauer <roland.rucky@xxxxxxxxx> wrote:

> Meaning the rbwork pointer is not null, but also not a valid pointer.
> Subtracting offset of the wait_index gives me address 0x178, which
> sure seems wrong.

Hmm, I wonder if the buffer got freed somehow. Not sure how that would
happen, as you can't free the buffer if something is opened on it.

>
> I think I will try a gdb session with this kernel (but I have not done
> this for a long time, might take me a while to get it working).

If this is fully reproducible, could you run strace -f on rasdaemon to
see what it is doing before it crashed?

That could be very useful. At least I may be able to create a
reproducer, as my rasdaemon is working fine.

-- Steve