PR fortran/95530, PR fortran/95537 - Buffer overflows with long symbols

The testcases for PR95090 and PR95106 trigger buffer overflows with long
symbols that were found with an instrumented compiler.  Enlarge the
affected buffers, and add checks that the buffers will suffice.

2020-06-05  Harald Anlauf  <anlauf@gmx.de>

gcc/fortran/
	PR fortran/95530
	PR fortran/95537
	* decl.c (gfc_match_decl_type_spec): Enlarge buffer, and enhance
	string copy to detect buffer overflow.
	* gfortran.h (gfc_common_head): Enlarge buffer.
	* trans-common.c (finish_equivalences): Enhance string copy to
	detect buffer overflow.

diff --git a/gcc/fortran/decl.c b/gcc/fortran/decl.c
index 3ad5559..1c1626d 100644 (file)
--- a/gcc/fortran/decl.c
+++ b/gcc/fortran/decl.c
@@ -4094,7 +4094,8 @@ match_byte_typespec (gfc_typespec *ts)
 match
 gfc_match_decl_type_spec (gfc_typespec *ts, int implicit_flag)
 {
-  char name[GFC_MAX_SYMBOL_LEN + 1];
+  /* Provide sufficient space to hold "pdtsymbol".  */
+  char name[GFC_MAX_SYMBOL_LEN + 1 + 3];
   gfc_symbol *sym, *dt_sym;
   match m;
   char c;
@@ -4284,7 +4285,11 @@ gfc_match_decl_type_spec (gfc_typespec *ts, int implicit_flag)
            return m;
          gcc_assert (!sym->attr.pdt_template && sym->attr.pdt_type);
          ts->u.derived = sym;
-         strcpy (name, gfc_dt_lower_string (sym->name));
+         const char* lower = gfc_dt_lower_string (sym->name);
+         size_t len = strnlen (lower, sizeof (name));
+         gcc_assert (len < sizeof (name));
+         memcpy (name, lower, len);
+         name[len] = '\0';
        }
 
       if (sym && sym->attr.flavor == FL_STRUCT)

diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 5af4484..0ef7b1b 100644 (file)
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1677,7 +1677,8 @@ typedef struct gfc_common_head
   char use_assoc, saved, threadprivate;
   unsigned char omp_declare_target : 1;
   unsigned char omp_declare_target_link : 1;
-  char name[GFC_MAX_SYMBOL_LEN + 1];
+  /* Provide sufficient space to hold "symbol.eq.1234567890".  */
+  char name[GFC_MAX_SYMBOL_LEN + 1 + 14];
   struct gfc_symbol *head;
   const char* binding_label;
   int is_bind_c;

diff --git a/gcc/fortran/trans-common.c b/gcc/fortran/trans-common.c
index 3775a8b..1acc336 100644 (file)
--- a/gcc/fortran/trans-common.c
+++ b/gcc/fortran/trans-common.c
@@ -1314,7 +1314,11 @@ finish_equivalences (gfc_namespace *ns)
              c->where = ns->proc_name->declared_at;
            else if (ns->is_block_data)
              c->where = ns->sym_root->n.sym->declared_at;
-           strcpy (c->name, z->module);
+
+           size_t len = strlen (z->module);
+           gcc_assert (len < sizeof (c->name));
+           memcpy (c->name, z->module, len);
+           c->name[len] = '\0';
          }
        else
          c = NULL;