Re: mm/sched/net: BUG when running simple code

From: Dan Aloni
Date: Fri Jun 13 2014 - 01:26:40 EST


On Fri, Jun 13, 2014 at 07:55:55AM +0300, Dan Aloni wrote:
> > that theory went away. (also confirmed by not finding a netlink module.)
> >
> > What about the kernel .text overflowing into the modules space? The loader
> > checks for that, but can something like that happen after everything is
> > up and running? I'll look into that tomorrow.
>
> The kernel .text needs to be more than 512MB for the overlap to happen.
>
> ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0
>
> Also, it is bizarre that symbol resolution resolved ffffffffa0f12560 to
> a symbol that is in module space where af_netlink.o is surely not because of
> "obj-y := af_netlink.o" in the Makefile.
>
> What does your /proc/kallsyms show when sorted with regards to the symbols
> in question?
>
> Also curious are the addresses you have on the stack:
>
> > [ 516.309720] Stack:
> > [ 516.309720] ffff8803fc85ff18 ffff8803fc85ff18 ffff8803fc85fef8 8900200549908020
> > [ 516.309720] ffff8803fc85ff18 ffffffff9ff66470 ffff8803fc85ff18 0000000000000037
> > [ 516.309720] ffff8803fc85ff78 ffffffff9ff69d26 0000000000000037 0000000000000004
>[..]

Oh, just figured about the new kASLR feature that got enabled
recently, it explains the addresses, but there was supposed to be a
line for it in the Oops, so I'm puzzled.

--
Dan Aloni
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