Re: Wanted: simple, safe x86 stack overflow detection

[Chuck Ebbert <cebbert@redhat.com>]

Bill Irwin wrote:
> On Wed, Feb 28, 2007 at 09:41:44PM +0100, Andi Kleen wrote:
>> I suppose one could have a CONFIG_DEBUG_STACK_OVERFLOW that gets
>> the stacks from vmalloc which would catch any overflow with its
>> guard pages. This is you would need to change __pa() to handle
>> that too because there might be still some drivers that do
>> DMA on stack addresses.  Would be somewhat ugly but doable.
>> But I have my doubts it is worth it again -- in my experience static
>> analysis works well enough to trace them down and 
>> there are not that many anyways.
> 
> In case anyone wants them, patches against v2.6.21-rc2-116-gbb648a0
> for this are available from http://oss.oracle.com/~wli/stack_paranoia/


> Chuck, is any of this of any use to you?


I said "simple." :)

In the 4k/4k stack i386 kernel, is there any fundamental reason it
can't be 4k/8k? We seem to be mostly hitting problems in overflowing
the IRQ stack... I think. Overhead would only be 4k per CPU for that.