[Bug c++/60750] double free after std::move on string inside throw when compiled with optimization

[trippels at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60750

Markus Trippelsdorf <trippels at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |trippels at gcc dot gnu.org

--- Comment #2 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
-fsanitize=address shows:

markus@x4 tmp % g++ -g -fsanitize=address -std=c++11 -O2 sample.cpp
markus@x4 tmp % ./a.out
=================================================================
==568==ERROR: AddressSanitizer: heap-use-after-free on address 0x60300000eff0
at pc 0x4014b0 bp 0x7fff5e3564a0 sp 0x7fff5e356498
READ of size 4 at 0x60300000eff0 thread T0
    #0 0x4014af in __exchange_and_add_single
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/ext/atomicity.h:67
    #1 0x4014af in __exchange_and_add_dispatch
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/ext/atomicity.h:84
    #2 0x4014af in std::string::_Rep::_M_dispose(std::allocator<char> const&)
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/bits/basic_string.h:246
    #3 0x4011aa in std::string::_Rep::_M_dispose(std::allocator<char> const&)
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/bits/basic_string.h:240
    #4 0x4011aa in ~basic_string
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/bits/basic_string.h:547
    #5 0x4011aa in main /var/tmp/sample.cpp:13
    #6 0x7f10d26e6faf in __libc_start_main (/lib/libc.so.6+0x1ffaf)
    #7 0x401354 (/var/tmp/a.out+0x401354)

0x60300000eff0 is located 16 bytes inside of 30-byte region
[0x60300000efe0,0x60300000effe)
freed by thread T0 here:
    #0 0x7f10d2d2bb97 in free
(/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.0/libasan.so.1+0x5eb97)
    #1 0x7f10d3b88809 in std::string::_Rep::_M_dispose(std::allocator<char>
const&)
/var/tmp/gcc_build_dir/x86_64-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:249
    #2 0x7f10d3b88809 in std::string::_M_mutate(unsigned long, unsigned long,
unsigned long)
/var/tmp/gcc_build_dir/x86_64-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc:487

previously allocated by thread T0 here:
    #0 0x7f10d2d2bdcf in malloc
(/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.0/libasan.so.1+0x5edcf)
    #1 0x7f10d3b28b97 in operator new(unsigned long)
../../../../gcc/libstdc++-v3/libsupc++/new_op.cc:49

SUMMARY: AddressSanitizer: heap-use-after-free
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/ext/atomicity.h:67
__exchange_and_add_single
Shadow bytes around the buggy address:
  0x0c067fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9dd0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9de0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c067fff9df0: fa fa fa fa fa fa fa fa fa fa fa fa fd fd[fd]fd
  0x0c067fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9e30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9e40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Contiguous container OOB:fc
  ASan internal:           fe
==568==ABORTING

markus@x4 tmp % g++ -g -fsanitize=address -std=c++11 -O1 sample.cpp
markus@x4 tmp % ./a.out
=================================================================
==754==ERROR: AddressSanitizer: attempting double-free on 0x60300000efe0 in
thread T0:
    #0 0x7f78aae87b97 in free
(/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.0/libasan.so.1+0x5eb97)
    #1 0x4012b6 in ~basic_string
/var/tmp/gcc_test/usr/local/include/c++/4.9.0/bits/basic_string.h:547
    #2 0x4012b6 in main /var/tmp/sample.cpp:13
    #3 0x7f78aa842faf in __libc_start_main (/lib/libc.so.6+0x1ffaf)
    #4 0x401028 (/var/tmp/a.out+0x401028)

0x60300000efe0 is located 0 bytes inside of 30-byte region
[0x60300000efe0,0x60300000effe)
freed by thread T0 here:
    #0 0x7f78aae87b97 in free
(/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.0/libasan.so.1+0x5eb97)
    #1 0x7f78abce4809 in std::string::_Rep::_M_dispose(std::allocator<char>
const&)
/var/tmp/gcc_build_dir/x86_64-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.h:249
    #2 0x7f78abce4809 in std::string::_M_mutate(unsigned long, unsigned long,
unsigned long)
/var/tmp/gcc_build_dir/x86_64-unknown-linux-gnu/libstdc++-v3/include/bits/basic_string.tcc:487

previously allocated by thread T0 here:
    #0 0x7f78aae87dcf in malloc
(/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.0/libasan.so.1+0x5edcf)
    #1 0x7f78abc84b97 in operator new(unsigned long)
../../../../gcc/libstdc++-v3/libsupc++/new_op.cc:49

SUMMARY: AddressSanitizer: double-free ??:0 free
==754==ABORTING
markus@x4 tmp %