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From: Lee <ler762 AT gmail DOT com>
Date: Tue, 3 Mar 2020 01:17:15 -0500
Message-ID: <CAD8GWsvCymn5Q4ABABMc5akv+YgfQ9NgyPz5THXuPgzWrTredw@mail.gmail.com>
Subject: Re: ASLR revisited
To: cygwin AT cygwin DOT com
Content-Type: text/plain; charset="UTF-8"
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On 3/2/20, John Selbie  wrote:
> And I just discovered that recompiling with this added to the g++ command
> line:
>
>  -Xlinker --dynamicbase
>
> Seems to work. Or at the least, triggers the process to show up in Process
> Explorer as ASLR?
>
> Good idea to continue with this?

I haven't looked at this in ages, but for gcc I use

LDFLAGS="${LDFLAGS} -Wl,--nxcompat"
# https://en.wikipedia.org/wiki/Data_Execution_Prevention
#   Enable DEP with -Wl,--nxcompat

LDFLAGS="${LDFLAGS} -Wl,--dynamicbase,--export-all-symbols"
# https://en.wikipedia.org/wiki/Address_space_layout_randomization
# https://stackoverflow.com/questions/24283918/how-can-i-enable-aslr-dep-and-safeseh-on-an-exe-in-codeblocks-using-mingw
#   ASLR with gcc has a problem: -Wl,--dynamicbase doesn't emit the
necessary relocation table.
#   As a workaround, you can pass -Wl,--dynamicbase,--export-all-symbols

Regards,
Lee

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