https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84052
Bug ID: 84052
Summary: Using Randomizing structure layout plugin in linux
kernel compilation doesn't generate proper debuginfo
Product: gcc
Version: 7.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: caoj.fnst at cn dot fujitsu.com
Target Milestone: ---
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin
--enable-initfini-array --with-isl --enable-libmpx
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686
--build=x86_64-redhat-linux
Thread model: posix
gcc version 7.2.1 20170915 (Red Hat 7.2.1-2) (GCC)
Recently, linux kernel introduced a security feature[*] to randomize the layout
of some crucial structures during compilation.
[*]https://lwn.net/Articles/722293/
FYI: the plugin related source files locate:
scripts/gcc-plugins/Makefile
scripts/gcc-plugins/gen-random-seed.sh
scripts/gcc-plugins/randomize_layout_plugin.c
of linux kernel source.
After enable/disable this feature, I use "gdb vmlinux" to examine the
debuginfo, and find that the output of "ptype struct xxx"(xxx is the randomized
structure like uts_namespace) in both condition are identical, which feels like
a bug to me. And this result would affect other utility like crash tool.
