Answer from @Dolphin isn't complete as it produces error from make: Makeconfig:42: *** missing separator. Stop.

In my case, to I had to do following:

# Check GLIBC_2.29
ldd --version | head -n1

# Build GLIBC_2.29 from sources
sudo apt-get install gawk bison -y
wget -c https://ftp.gnu.org/gnu/glibc/glibc-2.34.tar.gz
tar -zxvf glibc-2.34.tar.gz && cd glibc-2.34
mkdir glibc-build && cd glibc-build
../configure --prefix=/opt/glibc-2.34
make 
sudo make install

P.S. If you are trying to run ord just try building from sources, it's much simpler than upgrading ubuntu or recompiling GLIBC

Building on Shalini's answer,

#!/bin/bash

SOFTWARE_NAME=$1
SOFTWARE_VERSION=$2

export DOWNLOAD_INSTALL_DIR=$SOFTWARE_NAME-$SOFTWARE_VERSION-download-install
if [ -f $DOWNLOAD_INSTALL_DIR ];
then
    rm -fr $DOWNLOAD_INSTALL_DIR
    echo "Remove $DOWNLOAD_INSTALL_DIR"
fi

mkdir $HOME/$DOWNLOAD_INSTALL_DIR/ && cd $HOME/$DOWNLOAD_INSTALL_DIR

echo "Current directory at $PWD"

export DOWNLOADED_TAR=$HOME/$DOWNLOAD_INSTALL_DIR/$SOFTWARE_NAME-$SOFTWARE_VERSION.tar.gz
if [ ! -f $DOWNLOADED_TAR ]; then
    wget https://ftp.gnu.org/gnu/$SOFTWARE_NAME/$SOFTWARE_NAME-$SOFTWARE_VERSION.tar.gz -P $HOME/$DOWNLOAD_INSTALL_DIR
    echo "Software is downloaded: $SOFTWARE_NAME, version = $SOFTWARE_VERSION "
else
    echo "Software is ALREADY downloaded: $SOFTWARE_NAME, version = $SOFTWARE_VERSION at $DOWNLOADED_TAR"
fi
tar -xvzf $DOWNLOADED_TAR -C $HOME/$DOWNLOAD_INSTALL_DIR
mkdir $HOME/$DOWNLOAD_INSTALL_DIR/build
export SOURCE_DIR=$HOME/$DOWNLOAD_INSTALL_DIR/$SOFTWARE_NAME-$SOFTWARE_VERSION-install
mkdir $SOURCE_DIR
cd $HOME/$DOWNLOAD_INSTALL_DIR/build
~/$DOWNLOAD_INSTALL_DIR/$SOFTWARE_NAME-$SOFTWARE_VERSION/configure --prefix=$SOURCE_DIR
make
make install

export SOFTWARE_PATH=$HOME/$DOWNLOAD_INSTALL_DIR/$SOFTWARE_NAME-$SOFTWARE_VERSION-install/bin/$SOFTWARE_NAME
if [ -f $SOFTWARE_PATH ]; then
    echo "Software is found: $SOFTWARE_NAME, version = $SOFTWARE_VERSION at $SOFTWARE_PATH"
    mv $SOFTWARE_PATH $GRAND_ROOT_BIN
fi

You can use the script like so bash script-name.sh bison 3.8 for downloading GNU's bison with version number 3.8.

I wouldn't install it, but unpack it in some work directory and refer to it via LD_LIBRARY_PATH. Downgrading your libc6 package can be quite problematic.

Your customer should be able to supply you with their libc6 version. It might, however, be advisable to use the libc6-dbg package which includes debug symbols. Unfortunately the 7u4 version is an older one and not available anymore.

In my situation, the error appears when I try to run an application (compiled on Ubuntu 12.04 LTS) using GLIBC_2.14 on Debian Wheezy (which installs glibc 2.13 by default).

I use a tricky way to run it, and get correct result:

1. Download libc6 and libc6-dev from Ubuntu 12.04 LTS

2. Run dpkg command to install them into a directory (/home/user/fakeroot/ for example):

   $ dpkg -x libc6-dev_2.15-0ubuntu10.6_amd64.deb /home/user/fakeroot/
   $ dpkg -x libc6_2.15-0ubuntu10.6_amd64.deb /home/user/fakeroot/
   

3. Run your command with specified LD_LIBRARY_PATH:

   $ LD_LIBRARY_PATH=/home/user/fakeroot/lib/x86_64-linux-gnu/ YOUR_COMMAND
   

4. My application only uses memcpy() from GLIBC_2.14, and it works.

   I don't know whether it will work successfully for other applications.