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re: port-amd64/50989: Some programs in base dump dores with SIGILL

Christos Zoulas writes:
> On Mar 21,  5:25pm, (matthew green) wrote:
> -- Subject: re: port-amd64/50989: Some programs in base dump dores with SIGIL
> |  i have not seen any problem with GCC 5.3.  i'm happily running X11 with
> |  a bunch of GL and ssh on my amd4 box with a fully GCC 5.3 compiled by
> |  a GCC 5.3 world (though my pkgsrc build failed at around 690 packages
> |  i haven't looked at why yet -- though those were a 5.3 world that was
> |  compiled by 4.8.)
> There is something wrong with the old gcc and the processor detection
> code. It probably runs through the unoptimized mmx/avr code or it gets
> lucky with stack alignment. In my 5.3 tests sshd worked and ssh didn't.
> When I changed the stack offset by adding +8, ssh worked and sshd broke.
> With the new assembly code, both work (sha) but appears that the other
> assembly stubs are broken.

when people running 4.8 update to your new libcrypto all their apps
die in libcrypto with an unaligned stack.

when you changed the stack offset (you actually subtracted 40) you
only fixed the problem for the broken cases, but the working cases
you broken those.  sshd and ssh have some difference in their
setup or environment some how, and one of them has the stack
misaligned.  i don't see how aslr stack would do it cuz as far as
i can tell it leave the bottom 12 bits of the stack alone (ie, it
only moves the page number.)  i don't know what is wrong, but i'm
not seeing the problems you are.


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