[Bug libquadmath/99203] Undefined behaviour in libquadmath file print_fp.c function __quadmath_printf_fp

[marxin at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99203

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |63426
     Ever confirmed|0                           |1
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-02-23

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, full backtrace:

/home/marxin/Programming/gcc2/libquadmath/printf/printf_fp.c:762:4: runtime
error: passing zero to ctz(), which is not a valid argument
    #0 0x7ffff719692b in __quadmath_printf_fp
/home/marxin/Programming/gcc2/libquadmath/printf/printf_fp.c:762
    #1 0x7ffff71d6884 in quadmath_snprintf
/home/marxin/Programming/gcc2/libquadmath/printf/quadmath-printf.c:266
    #2 0x7ffff75ccbab  (/usr/lib64/libgfortran.so.5+0x252bab)
    #3 0x7ffff75d07df  (/usr/lib64/libgfortran.so.5+0x2567df)
    #4 0x7ffff75c72b4  (/usr/lib64/libgfortran.so.5+0x24d2b4)
    #5 0x7ffff75c7973  (/usr/lib64/libgfortran.so.5+0x24d973)
    #6 0x400d85 in checkfmt.0
(/home/marxin/Programming/testcases/a.out+0x400d85)
    #7 0x40160e in MAIN__ (/home/marxin/Programming/testcases/a.out+0x40160e)
    #8 0x4024e6 in main (/home/marxin/Programming/testcases/a.out+0x4024e6)
    #9 0x7ffff6fc9b24 in __libc_start_main (/lib64/libc.so.6+0x27b24)
    #10 0x40096d in _start (/home/marxin/Programming/testcases/a.out+0x40096d)


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63426
[Bug 63426] [meta-bug] Issues found with -fsanitize=undefined