#703: all binaries built by ghc have executable stacks
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Reporter: duncan | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Driver | Version: 6.4.1
Severity: normal | Keywords:
Os: Linux | Difficulty: Moderate (1 day)
Architecture: Multiple |
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= Non-executable stacks =
The GNU toolchain supports marking object files that do not need to use an
executable stack. Currently all object files produced by GHC lack these
notes and so the linker defaults to using an executable stack for the
resulting binary.
This makes some people grumpy. In particular it makes the Gentoo QA people
grumpy. :-)
'''The long story''':
http://www.gentoo.org/proj/en/hardened/gnu-stack.xml
'''The quick story''':
Every .S file produced by ghc should include:
{{{
.section .note.GNU-stack,"",@progbits
}}}
Currently this does not happen for either -fasm or -fvia-C.
== For -fasm ==
ghc simply does not emit the .section .note.GNU-stack stuff into the
assembly output.
== For -fvia-C ==
ghc emits C which is then compiled by gcc. The resulting .raw_s file does
contain the .section .note.GNU-stack. However ghc then runs the generated
assembly through the "evil mangler" which doesn't grok the .section
.note.GNU-stack and does not emit it to the final assembly file.
So the solution is to get ghc to emit the .note.GNU-stack in it's native
code geneerator and to modify the evil mangler to pass the .note.GNU-stack
through to the output.
We may still have a problem with the "split objs" feature (which ghc uses
for its own libraries). Hopefully it'd just be a matter of adding .note
.GNU-stack to each .s file that is spat out by ghc -split-objs.
----
For reference see http://bugs.gentoo.org/show_bug.cgi?id=123698
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/703>
GHC <http://www.haskell.org/ghc/>
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