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Re: Differences between zelenka and zandonai


am Sun, Oct 31, 2010 at 08:54:10AM +0100 hast du folgendes geschrieben:
> Firefox uses a technique they call "frame poisoning" to mitigate
> dangling pointer bugs. It reserves a poison area at a fixed location
> in the address space (and tries other places if that can't be done)
> and makes dangling pointers point there so that the application ends
> up crashing instead of being exploitable.
> There is validation test in their test suite that verifies if that
> technique works properly. While upstream version doesn't support s390,
> adding support for it is pretty straightforward. The only problem I have
> now is that while this works properly on zelenka, it doesn't work on
> zandonai during the test suite run part of the build.
> Is there a difference in the kernel or hardware that would explain this
> behaviour?

they are hosted on the same physical box, so there's no difference in hardware
at all.  However, zandonai runs a backports kernel (2.6.32-bpo.5-s390x), and
zelenka runs a release kernel (2.6.26-2-s390x).  I don't know why that is.

> I'm attaching the test program in question. It can be simply built with
> g++ -o TestPoisonArea TestPoisonArea.cpp

Simly compiling and running it does seem to work, however.

(sid-s390-sbuild)buildd@zandonai:/build$ g++ -o TestPoisonArea TestPoisonArea.cpp
(sid-s390-sbuild)buildd@zandonai:/build$ ./TestPoisonArea
INFO | negative control allocated at 0x77fd9000
INFO | positive control allocated at 0x77cac000
INFO | poison area assumed at 0xf0dea000 (preferred addr)
TEST-PASS | reading negative control
TEST-PASS | executing negative control
TEST-PASS | writing negative control
TEST-PASS | reading positive control | Segmentation fault
TEST-PASS | executing positive control | Segmentation fault
TEST-PASS | writing positive control | Segmentation fault
TEST-PASS | reading poison area | Segmentation fault
TEST-PASS | executing poison area | Segmentation fault
TEST-PASS | writing poison area | Segmentation fault

Kind regards,
Philipp Kern

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