[Bug demangler/84950] New: UBSAN: libiberty/cplus-dem.c:4430:3: runtime error: null pointer passed as argument 2, which is declared to never be null

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84950

            Bug ID: 84950
           Summary: UBSAN: libiberty/cplus-dem.c:4430:3: runtime error:
                    null pointer passed as argument 2, which is declared
                    to never be null
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: demangler
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
            Blocks: 63426
  Target Milestone: ---

Following causes the run-time error:

$ cat /tmp/todo

_Q.__0
::Q.(void)
$ ./libiberty/testsuite/test-demangle < /tmp/todo
../../libiberty/cplus-dem.c:4430:3: runtime error: null pointer passed as
argument 2, which is declared to never be null
    #0 0x402378 in remember_Ktype ../../libiberty/cplus-dem.c:4430
    #1 0x41bd85 in demangle_class ../../libiberty/cplus-dem.c:2688
    #2 0x41bd85 in demangle_signature ../../libiberty/cplus-dem.c:1556
    #3 0x41f211 in internal_cplus_demangle ../../libiberty/cplus-dem.c:1257
    #4 0x40cc3e in cplus_demangle ../../libiberty/cplus-dem.c:918
    #5 0x404a2c in main ../../../libiberty/testsuite/test-demangle.c:317
    #6 0x7ffff707ca86 in __libc_start_main (/lib64/libc.so.6+0x21a86)
    #7 0x405269 in _start
(/home/marxin/Programming/gcc/objdir3/libiberty/testsuite/test-demangle+0x405269)


Referenced Bugs:

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