Fixes #709, format() adds erronous thousands delimiter #5
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There was an off by one error in the fb_hProcessMask function (which needs to be refactored badly I think.)
dkl
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Jul 18, 2022
CLEAR takes the "object" to clear by reference, not an address by value. The extra @ (address-of) lead to clearing a temp var on stack (and likely overflowing it) instead of clearing the wanted variable, i.e. undefined behaviour. Reported at: freebasic#382 gcc AddressSanitizer finds this issue aswell: ==279298==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fffb16875e8 at pc 0x7fb7f4a01c23 bp 0x7fffb16874a0 sp 0x7fffb1686c48 WRITE of size 200 at 0x7fffb16875e8 thread T0 #0 0x7fb7f4a01c22 in __interceptor_memset ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:799 freebasic#1 0xa3fb11 in TESTS::FBC_TESTS::UDT_WSTRING_::MIDSTMT::ASCII() (/home/daniel/fb/fbc/tests/fbc-tests+0xa3fb11) freebasic#2 0xcc536c in FBCU::RUN_TESTS(bool, bool) src/fbcunit.bas:649 freebasic#3 0xcc134e in main (/home/daniel/fb/fbc/tests/fbc-tests+0xcc134e) freebasic#4 0x7fb7f4506d8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58 freebasic#5 0x7fb7f4506e3f in __libc_start_main_impl ../csu/libc-start.c:392 freebasic#6 0x413364 in _start (/home/daniel/fb/fbc/tests/fbc-tests+0x413364) Fixes: 135f364 "udt-wstring: MID statement will accept UDT as Z|WSTRING"
dkl
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to dkl/fbc
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Jul 18, 2022
Given
dim e1 as wstring * BUFFERSIZE
dim n1 as integer = BUFFERSIZE
then e1[n1] is an out-of-bounds access. I'm not entirely sure if the
change is sane with regards to the intent of the code (maybe e1 is
supposed to be BUFFERSIZE + 1?), but least it's not overflowing anymore.
Found with gcc AddressSanitizer:
[...]
==325124==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd6b7ecd28 at pc 0x000000b97cfb bp 0x7ffd6b7ec800 sp 0x7ffd6b7ec7f0
WRITE of size 4 at 0x7ffd6b7ecd28 thread T0
#0 0xb97cfa in TESTS::FBC_TESTS::WSTRING_::MIDSTMT::ASCII() wstring/midstmt.bas:86
freebasic#1 0xc56259 in FBCU::RUN_TESTS(bool, bool) src/fbcunit.bas:649
freebasic#2 0xc52533 in main (/home/daniel/fb/fbc/tests/fbc-tests+0xc52533)
freebasic#3 0x7fe4d3ddad8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
freebasic#4 0x7fe4d3ddae3f in __libc_start_main_impl ../csu/libc-start.c:392
freebasic#5 0x4082e4 in _start (/home/daniel/fb/fbc/tests/fbc-tests+0x4082e4)
Address 0x7ffd6b7ecd28 is located in stack of thread T0 at offset 1000 in frame
#0 0xb97420 in TESTS::FBC_TESTS::WSTRING_::MIDSTMT::ASCII() wstring/midstmt.bas:70
This frame has 8 object(s):
[32, 100) 'DST$1'
[144, 212) 'SRC$1'
[256, 456) 'W1$8'
[528, 728) 'W2$8'
[800, 1000) 'E1$8' <== Memory access at offset 1000 overflows this variable
[1072, 1272) 'W1$10'
[1344, 1544) 'W2$10'
[1616, 1816) 'E1$10'
[...]
Fixes: 135f364 "udt-wstring: MID statement will accept UDT as Z|WSTRING"
dkl
added a commit
to dkl/fbc
that referenced
this pull request
Jul 18, 2022
CLEAR takes the "object" to clear by reference, not an address by value. The extra @ (address-of) lead to clearing a temp var on stack (and likely overflowing it) instead of clearing the wanted variable, i.e. undefined behaviour. Reported at: freebasic#382 gcc AddressSanitizer finds this issue aswell: ``` ==279298==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fffb16875e8 at pc 0x7fb7f4a01c23 bp 0x7fffb16874a0 sp 0x7fffb1686c48 WRITE of size 200 at 0x7fffb16875e8 thread T0 #0 0x7fb7f4a01c22 in __interceptor_memset ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:799 freebasic#1 0xa3fb11 in TESTS::FBC_TESTS::UDT_WSTRING_::MIDSTMT::ASCII() (/home/daniel/fb/fbc/tests/fbc-tests+0xa3fb11) freebasic#2 0xcc536c in FBCU::RUN_TESTS(bool, bool) src/fbcunit.bas:649 freebasic#3 0xcc134e in main (/home/daniel/fb/fbc/tests/fbc-tests+0xcc134e) freebasic#4 0x7fb7f4506d8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58 freebasic#5 0x7fb7f4506e3f in __libc_start_main_impl ../csu/libc-start.c:392 freebasic#6 0x413364 in _start (/home/daniel/fb/fbc/tests/fbc-tests+0x413364) ``` Fixes: 135f364 "udt-wstring: MID statement will accept UDT as Z|WSTRING"
dkl
added a commit
to dkl/fbc
that referenced
this pull request
Jul 18, 2022
Given
dim e1 as wstring * BUFFERSIZE
dim n1 as integer = BUFFERSIZE
then e1[n1] is an out-of-bounds access. I'm not entirely sure if the
change is sane with regards to the intent of the code (maybe e1 is
supposed to be BUFFERSIZE + 1?), but least it's not overflowing anymore.
Found with gcc AddressSanitizer:
```
==325124==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd6b7ecd28 at pc 0x000000b97cfb bp 0x7ffd6b7ec800 sp 0x7ffd6b7ec7f0
WRITE of size 4 at 0x7ffd6b7ecd28 thread T0
#0 0xb97cfa in TESTS::FBC_TESTS::WSTRING_::MIDSTMT::ASCII() wstring/midstmt.bas:86
freebasic#1 0xc56259 in FBCU::RUN_TESTS(bool, bool) src/fbcunit.bas:649
freebasic#2 0xc52533 in main (/home/daniel/fb/fbc/tests/fbc-tests+0xc52533)
freebasic#3 0x7fe4d3ddad8f in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
freebasic#4 0x7fe4d3ddae3f in __libc_start_main_impl ../csu/libc-start.c:392
freebasic#5 0x4082e4 in _start (/home/daniel/fb/fbc/tests/fbc-tests+0x4082e4)
Address 0x7ffd6b7ecd28 is located in stack of thread T0 at offset 1000 in frame
#0 0xb97420 in TESTS::FBC_TESTS::WSTRING_::MIDSTMT::ASCII() wstring/midstmt.bas:70
This frame has 8 object(s):
[32, 100) 'DST$1'
[144, 212) 'SRC$1'
[256, 456) 'W1$8'
[528, 728) 'W2$8'
[800, 1000) 'E1$8' <== Memory access at offset 1000 overflows this variable
[1072, 1272) 'W1$10'
[1344, 1544) 'W2$10'
[1616, 1816) 'E1$10'
[...]
```
Fixes: 135f364 "udt-wstring: MID statement will accept UDT as Z|WSTRING"
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There was an off by one error in the fb_hProcessMask function (which needs
to be refactored badly I think), it would add the thousands separator at the front of any mod 3 length number string.