Fix another Rust demangling bugs (PR 105039)

Fix another Rust demangling bugs (PR 105039)

[Nick Clifton]

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Hi Guys,

   Attached is a proposed patch to fix another Rust demangling bug
   reported in PR 105039.  I would like to say that this is the
   last time that we will see this problem for the Rust demangler,
   but I am not that naive...

   OK to apply ?

Cheers
   Nick

[-- Attachment #2: pr105039.patch --]
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diff --git a/libiberty/rust-demangle.c b/libiberty/rust-demangle.c
index 3b24d63892a..d601182ac50 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

Re: Fix another Rust demangling bugs (PR 105039)

[Jeff Law]

On 3/24/2022 7:12 AM, Nick Clifton via Gcc-patches wrote:
> Hi Guys,
>
>   Attached is a proposed patch to fix another Rust demangling bug
>   reported in PR 105039.  I would like to say that this is the
>   last time that we will see this problem for the Rust demangler,
>   but I am not that naive...
>
>   OK to apply ?
OK.

There are days when I wonder if restructuring the demanglers to use 
loops or gotos to avoid the recursion would be a step forward.  But I'm 
not convinced the same kinds of inputs just hang rather than eating 
stack space until the limit is exhausted.  So it wouldn't be a 
significant QOI improvement.

jeff