[Buildroot] [PATCH RFC v2] gcc: improve checking of stack smashing support with uclibc

[Brendan Heading <brendanheading@gmail.com>]

Fixes:
http://autobuild.buildroot.net/results/123/123a5b3f72ba8c1a4aa1cea5b7b846a04fd4e923/
http://autobuild.buildroot.net/results/38c/38cfa4e7249a8770b06dbd392acba79303d3f9bc/

.. and others.

Improve GCC's checking of stack smashing support, by moving the check for
uclibc further up, and splitting the condition there so that stack smashing
support is tested in any case where uclibc is detected.

Signed-off-by: Brendan Heading <brendanheading@gmail.com>
---
v1 -> v2 : improved following comments from Arnout :
- reworked the conditional statement instead of adding a separate case
statement. This is a bit less intrusive.
- formatting etc. improvements
- still only fixing 4.7.4 - once we've got it right I'll port the patch
to the other versions

Patch V1 - this initial version only fixes 4.7.4 - wanted to check that
we are heading the right way before I fix all the other versions.

Note that I manually modified configure, rather than regenerating it from
configure.ac.

Original plan was to reverse the order of the existing __GLIBC_MINOR__ and
uclibc check. However, the uclibc check falls through if it does not
detect uclibc, so I figure it better to add the separate case statement.
---
 ...ing-of-stack-smashing-support-with-uclibc.patch | 81 ++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 package/gcc/4.7.4/920-gcc-improve-checking-of-stack-smashing-support-with-uclibc.patch

diff --git a/package/gcc/4.7.4/920-gcc-improve-checking-of-stack-smashing-support-with-uclibc.patch b/package/gcc/4.7.4/920-gcc-improve-checking-of-stack-smashing-support-with-uclibc.patch
new file mode 100644
index 0000000..31947a0
--- /dev/null
+++ b/package/gcc/4.7.4/920-gcc-improve-checking-of-stack-smashing-support-with-uclibc.patch
@@ -0,0 +1,81 @@
+From ff055a237ef91673a031bfe9dab743b01bd93d70 Mon Sep 17 00:00:00 2001
+From: Brendan Heading <brendanheading@gmail.com>
+Date: Mon, 28 Sep 2015 16:14:41 +0100
+Subject: [PATCH 1/1] Improve checking of stack-smashing support with uclibc
+
+Detect if uclibc has stack-smashing enabled, and fall out if it does not.
+
+A more comprehensive solution is to be proposed for upstream.
+
+Upstream-status: inappropriate
+Signed-off-by: Brendan Heading <brendanheading@gmail.com>
+---
+ gcc/configure    | 15 +++++++++------
+ gcc/configure.ac | 15 +++++++++------
+ 2 files changed, 18 insertions(+), 12 deletions(-)
+
+diff --git a/gcc/configure b/gcc/configure
+index 63cba0a..658a3e6 100755
+--- a/gcc/configure
++++ b/gcc/configure
+@@ -26806,17 +26806,20 @@ else
+ 	if $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC__[ 	]+([1-9][0-9]|[3-9])' \
+ 	   $target_header_dir/features.h > /dev/null; then
+ 	  gcc_cv_libc_provides_ssp=yes
++	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC__[ 	]+1' \
++	     $target_header_dir/features.h > /dev/null && \
++	     test -f $target_header_dir/bits/uClibc_config.h; then
++	      if $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC_HAS_SSP__[ 	]+1' \
++	        $target_header_dir/bits/uClibc_config.h > /dev/null; then
++	         gcc_cv_libc_provides_ssp=yes
++	      else
++	         gcc_cv_libc_provides_ssp=no
++	      fi
+ 	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC__[ 	]+2' \
+ 	     $target_header_dir/features.h > /dev/null \
+ 	     && $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC_MINOR__[ 	]+([1-9][0-9]|[4-9])' \
+ 	     $target_header_dir/features.h > /dev/null; then
+ 	  gcc_cv_libc_provides_ssp=yes
+-	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC__[ 	]+1' \
+-	     $target_header_dir/features.h > /dev/null && \
+-	     test -f $target_header_dir/bits/uClibc_config.h && \
+-	     $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC_HAS_SSP__[ 	]+1' \
+-	     $target_header_dir/bits/uClibc_config.h > /dev/null; then
+-	  gcc_cv_libc_provides_ssp=yes
+ 	fi
+       # all versions of Bionic support stack protector
+       elif test -f $target_header_dir/sys/cdefs.h \
+diff --git a/gcc/configure.ac b/gcc/configure.ac
+index ea1c147..7282ea4 100644
+--- a/gcc/configure.ac
++++ b/gcc/configure.ac
+@@ -4681,17 +4681,20 @@ AC_CACHE_CHECK(__stack_chk_fail in target C library,
+ 	if $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC__[ 	]+([1-9][0-9]|[3-9])' \
+ 	   $target_header_dir/features.h > /dev/null; then
+ 	  gcc_cv_libc_provides_ssp=yes
++	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC__[ 	]+1' \
++	     $target_header_dir/features.h > /dev/null && \
++	     test -f $target_header_dir/bits/uClibc_config.h; then
++	      if $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC_HAS_SSP__[ 	]+1' \
++	        $target_header_dir/bits/uClibc_config.h > /dev/null; then
++	         gcc_cv_libc_provides_ssp=yes
++	      else
++	         gcc_cv_libc_provides_ssp=no
++	      fi
+ 	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC__[ 	]+2' \
+ 	     $target_header_dir/features.h > /dev/null \
+ 	     && $EGREP '^[ 	]*#[ 	]*define[ 	]+__GLIBC_MINOR__[ 	]+([1-9][0-9]|[4-9])' \
+ 	     $target_header_dir/features.h > /dev/null; then
+ 	  gcc_cv_libc_provides_ssp=yes
+-	elif $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC__[ 	]+1' \
+-	     $target_header_dir/features.h > /dev/null && \
+-	     test -f $target_header_dir/bits/uClibc_config.h && \
+-	     $EGREP '^[ 	]*#[ 	]*define[ 	]+__UCLIBC_HAS_SSP__[ 	]+1' \
+-	     $target_header_dir/bits/uClibc_config.h > /dev/null; then
+-	  gcc_cv_libc_provides_ssp=yes
+ 	fi
+       # all versions of Bionic support stack protector
+       elif test -f $target_header_dir/sys/cdefs.h \
+-- 
+2.4.3
+
-- 
2.4.3