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From: DDoSolitary <ddosolitary AT gmail DOT com>
To: cygwin AT cygwin DOT com
Subject: -fstack-protector and -fstack-protector-all broken after updating to gcc-core-6.4.0-5
Message-ID: <2475a459-9ebb-488b-202f-8fb068adec25@gmail.com>
Date: Sun, 21 Jan 2018 16:30:07 +0800
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

The stack protector options are broken after updating gcc-core to 6.4.0-
5.

For example compiling the following C code with "gcc foo.cpp
- -fstack-protector-all" results in errors.

int main() {
	return 0;
}

/tmp/ccrXUPvn.o:foo.c:(.text+0x33): undefined reference to
`__stack_chk_fail'
/tmp/ccrXUPvn.o:foo.c:(.text+0x33): relocation truncated to fit:
R_X86_64_PC32 against undefined symbol `__stack_chk_fail'
/tmp/ccrXUPvn.o:foo.c:(.rdata$.refptr.__stack_chk_guard[.refptr.__stack_
chk_guard]+0x0):
undefined reference to `__stack_chk_guard'
collect2: error: ld returned 1 exit status

Downgrading gcc-core to 6.4.0-4 fixes the problem.

After checking the content of the package, I found out that
libssp-related files (libssp.a, libssp.h, etc) are missing. So I
copied libssp.a from the 6.4.0-4 package to
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0 and tried to re-compile the code
above with "gcc foo.cpp -fstack-protector-all -lssp" and it worked well.
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