[gcc r9-8665] PR fortran/95091 - Buffer overflows with submodules and long symbols

[gcc r9-8665] PR fortran/95091 - Buffer overflows with submodules and long symbols

[Harald Anlauf]

https://gcc.gnu.org/g:abfe42c1fb66a534290bd0a808c2d90842ee848b

commit r9-8665-gabfe42c1fb66a534290bd0a808c2d90842ee848b
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sun Jun 7 14:47:24 2020 +0200

    PR fortran/95091 - Buffer overflows with submodules and long symbols
    
    With submodules, name mangling results in long internal symbols.  This
    requires adjustment of the sizes of temporaries to avoid buffer overflows.
    
    2020-06-07  Harald Anlauf  <anlauf@gmx.de>
    
    gcc/fortran/
            PR fortran/95091
            * class.c (get_unique_type_string, gfc_hash_value): Enlarge
            buffers, and check whether the strings returned by
            get_unique_type_string() fit.
    
    (cherry picked from commit b342cfd648e6658363c7c8fef83af8f59dba1795)

Diff:
---
 gcc/fortran/class.c                   | 11 ++++++++---
 gcc/testsuite/gfortran.dg/pr95091.f90 | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/gcc/fortran/class.c b/gcc/fortran/class.c
index a8698f19cfb..1c1211a997e 100644
--- a/gcc/fortran/class.c
+++ b/gcc/fortran/class.c
@@ -501,8 +501,11 @@ get_unique_type_string (char *string, gfc_symbol *derived)
 static void
 get_unique_hashed_string (char *string, gfc_symbol *derived)
 {
-  char tmp[2*GFC_MAX_SYMBOL_LEN+2];
+  /* Provide sufficient space to hold "symbol.symbol_symbol".  */
+  char tmp[3*GFC_MAX_SYMBOL_LEN+3];
   get_unique_type_string (&tmp[0], derived);
+  size_t len = strnlen (tmp, sizeof (tmp));
+  gcc_assert (len < sizeof (tmp));
   /* If string is too long, use hash value in hex representation (allow for
      extra decoration, cf. gfc_build_class_symbol & gfc_find_derived_vtab).
      We need space to for 15 characters "__class_" + symbol name + "_%d_%da",
@@ -523,11 +526,13 @@ unsigned int
 gfc_hash_value (gfc_symbol *sym)
 {
   unsigned int hash = 0;
-  char c[2*(GFC_MAX_SYMBOL_LEN+1)];
+  /* Provide sufficient space to hold "symbol.symbol_symbol".  */
+  char c[3*GFC_MAX_SYMBOL_LEN+3];
   int i, len;
 
   get_unique_type_string (&c[0], sym);
-  len = strlen (c);
+  len = strnlen (c, sizeof (c));
+  gcc_assert (len < sizeof (c));
 
   for (i = 0; i < len; i++)
     hash = (hash << 6) + (hash << 16) - hash + c[i];
diff --git a/gcc/testsuite/gfortran.dg/pr95091.f90 b/gcc/testsuite/gfortran.dg/pr95091.f90
new file mode 100644
index 00000000000..1c48dca2f4a
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr95091.f90
@@ -0,0 +1,19 @@
+! { dg-do compile }
+! { dg-options "-fsecond-underscore" }
+! PR fortran/95091 - ICE in gfc_hash_value
+
+module m2345678901234567890123456789012345678901234567890123456789_123
+  type t2345678901234567890123456789012345678901234567890123456789_123
+  end type t2345678901234567890123456789012345678901234567890123456789_123
+  interface
+     module subroutine s2345678901234567890123456789012345678901234567890123456789_123 &
+          (x2345678901234567890123456789012345678901234567890123456789_123)
+    end
+  end interface
+end
+submodule(m2345678901234567890123456789012345678901234567890123456789_123) &
+     n2345678901234567890123456789012345678901234567890123456789_123
+  type, extends(t2345678901234567890123456789012345678901234567890123456789_123) :: &
+    u2345678901234567890123456789012345678901234567890123456789_123
+  end type
+end