https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62124
Bug ID: 62124
Summary: Out-of-bounds array access in optimized loop
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mmarino at gmail dot com
Created attachment 33313
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33313&action=edit
preprocessed file
Seg fault after running the following code (bounds are over-run) compiled with
optimization:
<snip>
#include <iostream>
int main(int, char**)
{
unsigned int mt[624];
std::cout << " Array status mt[] = " << std::endl;
for (size_t i=0; i<624; i+=5) {
std::cout << i << " " << mt[i] << " " << mt[i+1] << " " << mt[i+2] << " "
<< mt[i+3] << " " << mt[i+4] << std::endl;
}
std::cout << "----------------------------------------" << std::endl;
return 0;
}
</snip>
Output of run program (array values are of course junk):
> ./main
Array status mt[] =
0 0 0 3135122682 32562 3137320592
...
3275 774975802 1280245808 1146572868 1869098813 1831822701
3280 1918987623 7302761 791559519 1852399981 1831808512
Segmentation fault (core dumped)
>
Compiled with:
g++ -v -save-temps -Wall -Wextra -O3 -o main main.cc
-O2 gives the same problem.
Output of compiler:
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.2-19ubuntu1'
--with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap
--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-4.8-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-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 --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 4.8.2 (Ubuntu 4.8.2-19ubuntu1)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O3' '-o' 'main'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/cc1plus -E -quiet -v -imultiarch
x86_64-linux-gnu -D_GNU_SOURCE main.cc -mtune=generic -march=x86-64 -Wall
-Wextra -O3 -fpch-preprocess -fstack-protector -Wformat -Wformat-security -o
main.ii
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/4.8"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/4.8
/usr/include/x86_64-linux-gnu/c++/4.8
/usr/include/c++/4.8/backward
/usr/lib/gcc/x86_64-linux-gnu/4.8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O3' '-o' 'main'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/cc1plus -fpreprocessed main.ii -quiet
-dumpbase main.cc -mtune=generic -march=x86-64 -auxbase main -O3 -Wall -Wextra
-version -fstack-protector -Wformat -Wformat-security -o main.s
GNU C++ (Ubuntu 4.8.2-19ubuntu1) version 4.8.2 (x86_64-linux-gnu)
compiled by GNU C version 4.8.2, GMP version 5.1.3, MPFR version 3.1.2-p3,
MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (Ubuntu 4.8.2-19ubuntu1) version 4.8.2 (x86_64-linux-gnu)
compiled by GNU C version 4.8.2, GMP version 5.1.3, MPFR version 3.1.2-p3,
MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 26a7c0bd346d04102f6aea776e0cccc5
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O3' '-o' 'main'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
as -v --64 -o main.o main.s
GNU assembler version 2.24 (x86_64-linux-gnu) using BFD version (GNU Binutils
for Ubuntu) 2.24
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-O3' '-o' 'main'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/collect2 --sysroot=/ --build-id
--eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker
/lib64/ld-linux-x86-64.so.2 -z relro -o main
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o
-L/usr/lib/gcc/x86_64-linux-gnu/4.8
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib -L/lib/x86_64-linux-gnu
-L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib
-L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../.. main.o -lstdc++ -lm -lgcc_s -lgcc
-lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
