[gcc r13-1393] Add a recursion limit to the demangle_const function in the Rust demangler.

[gcc r13-1393] Add a recursion limit to the demangle_const function in the Rust demangler.

[Nick Clifton]

https://gcc.gnu.org/g:9234cdca6ee88badfc00297e72f13dac4e540c79

commit r13-1393-g9234cdca6ee88badfc00297e72f13dac4e540c79
Author: Nick Clifton <nickc@redhat.com>
Date:   Fri Jul 1 15:58:52 2022 +0100

    Add a recursion limit to the demangle_const function in the Rust demangler.
    
    libiberty/
            PR demangler/105039
            * rust-demangle.c (demangle_const): Add recursion limit.

Diff:
---
 libiberty/rust-demangle.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/libiberty/rust-demangle.c b/libiberty/rust-demangle.c
index bb58d900e27..36afcfae278 100644
--- a/libiberty/rust-demangle.c
+++ b/libiberty/rust-demangle.c
@@ -126,7 +126,7 @@ parse_integer_62 (struct rust_demangler *rdm)
     return 0;
 
   x = 0;
-  while (!eat (rdm, '_'))
+  while (!eat (rdm, '_') && !rdm->errored)
     {
       c = next (rdm);
       x *= 62;
@@ -1148,6 +1148,15 @@ demangle_const (struct rust_demangler *rdm)
   if (rdm->errored)
     return;
 
+  if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
+    {
+      ++ rdm->recursion;
+      if (rdm->recursion > RUST_MAX_RECURSION_COUNT)
+	/* FIXME: There ought to be a way to report
+	   that the recursion limit has been reached.  */
+	goto fail_return;
+    }
+
   if (eat (rdm, 'B'))
     {
       backref = parse_integer_62 (rdm);
@@ -1158,7 +1167,7 @@ demangle_const (struct rust_demangler *rdm)
           demangle_const (rdm);
           rdm->next = old_next;
         }
-      return;
+      goto pass_return;
     }
 
   ty_tag = next (rdm);
@@ -1167,7 +1176,7 @@ demangle_const (struct rust_demangler *rdm)
     /* Placeholder. */
     case 'p':
       PRINT ("_");
-      return;
+      goto pass_return;
 
     /* Unsigned integer types. */
     case 'h':
@@ -1200,18 +1209,20 @@ demangle_const (struct rust_demangler *rdm)
       break;
 
     default:
-      rdm->errored = 1;
-      return;
+      goto fail_return;
     }
 
-  if (rdm->errored)
-    return;
-
-  if (rdm->verbose)
+  if (!rdm->errored && rdm->verbose)
     {
       PRINT (": ");
       PRINT (basic_type (ty_tag));
     }
+
+ fail_return:
+  rdm->errored = 1;
+ pass_return:
+  if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
+    -- rdm->recursion;
 }
 
 static void