Fixes: #709, off by one error #6
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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
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"
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