編譯帶 debug info 的 glibc 源碼級調試

剛剛換了新系統（原本這些實驗是在另一台電腦上做的）

今天編譯 glibc，遇到的麻煩，以及解決方案

編譯系統一樣版本的 glibc 沒有遇到問題，直接編譯安裝成功

這些問題是我在編譯 glibc2.23 的時候遇到

1. 因為 匯編器 版本不同出的問題

這個問題我 patch 源碼

我查到的 完整的 patch：

diff --git a/package/glibc/0005-fix-binutils-2-29-build.patch b/package/glibc/0005-fix-binutils-2-29-build.patch
new file mode 100644
index 0000000..47fcd2f
--- /dev/null
+++ b/package/glibc/0005-fix-binutils-2-29-build.patch
@@ -0,0 +1,65 @@ 
+From: H.J. Lu <[e-mail]>
+Date: Fri, 23 Jun 2017 21:38:46 +0000 (-0700)
+Subject: Avoid .symver on common symbols [BZ #21666]
+X-Git-Tag: glibc-2.26~241
+X-Git-Url: https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff_plain;h=388b4f1a02f3a801965028bbfcd48d905638b797
+
+Avoid .symver on common symbols [BZ #21666]
+
+The .symver directive on common symbol just creates a new common symbol,
+not an alias and the newer assembler with the bug fix for
+
+https://sourceware.org/bugzilla/show_bug.cgi?id=21661
+
+will issue an error.  Before the fix, we got
+
+$ readelf -sW libc.so | grep "loc[12s]"
+  5109: 00000000003a0608     8 OBJECT  LOCAL  DEFAULT   36 loc1
+  5188: 00000000003a0610     8 OBJECT  LOCAL  DEFAULT   36 loc2
+  5455: 00000000003a0618     8 OBJECT  LOCAL  DEFAULT   36 locs
+  6575: 00000000003a05f0     8 OBJECT  GLOBAL DEFAULT   36 locs@GLIBC_2.2.5
+  7156: 00000000003a05f8     8 OBJECT  GLOBAL DEFAULT   36 loc1@GLIBC_2.2.5
+  7312: 00000000003a0600     8 OBJECT  GLOBAL DEFAULT   36 loc2@GLIBC_2.2.5
+
+in libc.so.  The versioned loc1, loc2 and locs have the wrong addresses.
+After the fix, we got
+
+$ readelf -sW libc.so | grep "loc[12s]"
+  6570: 000000000039e3b8     8 OBJECT  GLOBAL DEFAULT   34 locs@GLIBC_2.2.5
+  7151: 000000000039e3c8     8 OBJECT  GLOBAL DEFAULT   34 loc1@GLIBC_2.2.5
+  7307: 000000000039e3c0     8 OBJECT  GLOBAL DEFAULT   34 loc2@GLIBC_2.2.5
+
+	[BZ #21666]
+	* misc/regexp.c (loc1): Add __attribute__ ((nocommon));
+	(loc2): Likewise.
+	(locs): Likewise.
+
+Signed-off-by: Thomas Petazzoni <[e-mail]>
+[Backported from upstream commit
+388b4f1a02f3a801965028bbfcd48d905638b797, to fix the build with
+binutils 2.29.]
+---
+diff --git a/misc/regexp.c b/misc/regexp.c
+index 19d76c0..eaea7c3 100644
+--- a/misc/regexp.c
++++ b/misc/regexp.c
+@@ -29,14 +29,15 @@
+ 
+ #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_23)
+ 
+-/* Define the variables used for the interface.  */
+-char *loc1;
+-char *loc2;
++/* Define the variables used for the interface.  Avoid .symver on common
++   symbol, which just creates a new common symbol, not an alias.  */
++char *loc1 __attribute__ ((nocommon));
++char *loc2 __attribute__ ((nocommon));
+ compat_symbol (libc, loc1, loc1, GLIBC_2_0);
+ compat_symbol (libc, loc2, loc2, GLIBC_2_0);
+ 
+ /* Although we do not support the use we define this variable as well.  */
+-char *locs;
++char *locs __attribute__ ((nocommon));
+ compat_symbol (libc, locs, locs, GLIBC_2_0);
+ 
+ 

via：https://patchwork.ozlabs.org/patch/797471/

這個是我自己實際的 patch ：

diff --git a/glibc-2.23/misc/regexp.c b/glibc-2.23/misc/regexp.c
index f56d0c7..3b36682 100644
--- a/glibc-2.23/misc/regexp.c
+++ b/glibc-2.23/misc/regexp.c
@@ -30,14 +30,13 @@
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_23)
 
 /* Define the variables used for the interface.  */
-char *loc1 __attribute__ ((nocommon));
-char *loc2 __attribute__ ((nocommon));
-
+char *loc1;
+char *loc2;
 compat_symbol (libc, loc1, loc1, GLIBC_2_0);
 compat_symbol (libc, loc2, loc2, GLIBC_2_0);
 
 /* Although we do not support the use we define this variable as well.  */
-char *locs __attribute__ ((nocommon));
+char *locs;
 compat_symbol (libc, locs, locs, GLIBC_2_0);

patch 完編譯，安裝

sudo mkdir build
sudo cd build
sudo ../configure --prefix=/glibc/x64/2.23/ --disable-werror --enable-debug=yes
sudo make j8
sudo make install

x64 版 patch 完可以正常編譯安裝

2. 編譯 x86 版的時候又出問題

mkdir build
cd build
sudo ../configure --prefix=/glibc/x86/2.23/ --disable-werror --enable-debug=yes --host=i686-linux-gnu --build=i686-linux-gnu CC="gcc -m32" CXX="g++ -m32"

看報錯 __stack_chk_fail_local

這個函數是棧保護 cannary 的一個函數

直接把棧保護關掉 -fno-stack-protector

sudo mkdir build
sudo cd build
sudo ../configure --prefix=/glibc/x86/2.23/ --disable-werror --enable-debug=yes --host=i686-linux-gnu --build=i686-linux-gnu CC="gcc -m32 -fno-stack-protector" CXX="g++ -m32 -fno-stack-protector"
sudo make j8
sudo make install

編譯成功，安裝

我的系統內核是 5.5，glibc是 2.31，有的工具是依賴比較高的 glibc 版本，像是剛剛編譯好的 glibc2.23 直接 export LD_LIBRARY_PATH = 的話會造成很多工具用不了，像是這個

解決方案是利用 preload 或者用 pwntools， pwn_debug

LD_PRELOAD=/glibc/x64/2.23/lib/libc-2.23.so malloc_debug

運行起來后再用 gdb attach 上去

pwntools 我就不演示了