https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94975
Bug ID: 94975
Summary: Address sanitizations show heap-buffer-overflow with
class(*) allocated to character on assignment
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: vladimir.fuka at gmail dot com
Target Milestone: ---
With GCC 7-10 (bit libasan from 10)
class(*), allocatable :: p
p = "abc"
select type(p)
type is (character(*))
print *, p
end select
end
causes
> gfortran-10 star_character.f90 -fsanitize=address
> ./a.out
=================================================================
==12833==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x602000000071 at pc 0x7fa43e30e9b9 bp 0x7fffe526aa50 sp 0x7fffe526a200
WRITE of size 3 at 0x602000000071 thread T0
#0 0x7fa43e30e9b8 in __interceptor_memmove
(/usr/lib64/libasan.so.6+0x3b9b8)
#1 0x400ddc in __copy_character_1.0
(/home/lada/f/testy/bugs/a.out+0x400ddc)
#2 0x401078 in MAIN__ (/home/lada/f/testy/bugs/a.out+0x401078)
#3 0x401305 in main (/home/lada/f/testy/bugs/a.out+0x401305)
#4 0x7fa43d2f0349 in __libc_start_main (/lib64/libc.so.6+0x24349)
#5 0x400c99 in _start (/home/lada/f/testy/bugs/a.out+0x400c99)
0x602000000071 is located 0 bytes to the right of 1-byte region
[0x602000000070,0x602000000071)
allocated by thread T0 here:
#0 0x7fa43e37f3df in malloc (/usr/lib64/libasan.so.6+0xac3df)
#1 0x400fca in MAIN__ (/home/lada/f/testy/bugs/a.out+0x400fca)
#2 0x401305 in main (/home/lada/f/testy/bugs/a.out+0x401305)
#3 0x7fa43d2f0349 in __libc_start_main (/lib64/libc.so.6+0x24349)
SUMMARY: AddressSanitizer: heap-buffer-overflow
(/usr/lib64/libasan.so.6+0x3b9b8) in __interceptor_memmove
Shadow bytes around the buggy address:
0x0c047fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c047fff8000: fa fa 06 fa fa fa 07 fa fa fa 07 fa fa fa[01]fa
0x0c047fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8050: 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
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==12833==ABORTING
while
class(*), allocatable :: p
allocate(p, source = "abc")
select type(p)
type is (character(*))
print *, p
end select
end
is clean and prints "abc". That is also written with the former without
address sanitizations.
Tested on OpenSuSE Leap 15.1.
