[Bug binutils/24168] segment fault in nm-new in binutils-2.30

[zhangyn2012 at bupt dot edu.cn]

https://sourceware.org/bugzilla/show_bug.cgi?id=24168

--- Comment #2 from zhangyn2012 at bupt dot edu.cn ---
(In reply to Nick Clifton from comment #1)

Hi Nick,

>   How was the toolchain configured ?  Also, were you running these tests
>   on a 32-bit host or a 64-bit host ?

I ran the tests on a 64-bit host.

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
5.4.0-6ubuntu1~16.04.11' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.11)




> Are you able to use a debugger to narrow down what is going wrong ?

I debugged and found that in the loop of nm.c:983, when j increased to 44, a
null pointer dereference is triggered because though it checks r->sym_ptr_ptr
is not null, *r->sym_ptr_ptr is a null pointer. nm.c:989 accesses
*r->sym_ptr_ptr->section which causes the program to crash.

Program received signal SIGSEGV, Segmentation fault.
0x0000000000403b55 in print_symbol (address@hidden, sym=0x71a660,
ssiz
address@hidden, address@hidden) at nm.c:989
1: j = 44
2: r->sym_ptr_ptr = (struct bfd_symbol **) 0x71a8a8
3: *r->sym_ptr_ptr = (struct bfd_symbol *) 0x0

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