[Bug sanitizer/80166] SANITIZER_INTERCEPT_GETGROUPS modifies list when size is 0 Out-of-bounds write

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80166

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Another problem is that for a negative number, returned value is -1 (error).
And thus libsanitizer crashes:

==7910==ERROR: AddressSanitizer: negative-size-param: (size=-4)
    #0 0x7ff25bcd6a00 in __interceptor_getgroups
(/usr/lib64/libasan.so.3+0x50a00)
    #1 0x4009fb in main /home/marxin/Programming/testcases/pr80166.c:9
    #2 0x7ff25b901540 in __libc_start_main (/lib64/libc.so.6+0x20540)
    #3 0x400899 in _start
(/home/marxin/Programming/testcases/get_group+0x400899)