[Bug other/92456] New: libiberty/make-relative-prefix.c: read buffer overflow in split_directories()

[tim.ruehsen at gmx dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92456

            Bug ID: 92456
           Summary: libiberty/make-relative-prefix.c: read buffer overflow
                    in split_directories()
           Product: gcc
           Version: 9.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tim.ruehsen at gmx dot de
  Target Milestone: ---

Created attachment 47209
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47209&action=edit
Patch proposal to fix the issue

In L189
  if (dirs[num_dirs - 1] == NULL)
'num_dirs' can be 0 if name is an empty string.

Same in L129.

The attached patch fixes both.