[gcc r13-1452] Prevent another potential stack overflow issue when demangling a maliciouslt mangled Rust name.

[gcc r13-1452] Prevent another potential stack overflow issue when demangling a maliciouslt mangled Rust name.

[Nick Clifton]

https://gcc.gnu.org/g:1a770b01ef415e114164b6151d1e55acdee09371

commit r13-1452-g1a770b01ef415e114164b6151d1e55acdee09371
Author: Nick Clifton <nickc@redhat.com>
Date:   Mon Jul 4 11:05:03 2022 +0100

    Prevent another potential stack overflow issue when demangling a maliciouslt mangled Rust name.
    
    libiberty/
            * rust-demangle.c (demangle_path_maybe_open_generics): Add
            recursion limit.

Diff:
---
 libiberty/rust-demangle.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/libiberty/rust-demangle.c b/libiberty/rust-demangle.c
index 36afcfae278..d6daf23af27 100644
--- a/libiberty/rust-demangle.c
+++ b/libiberty/rust-demangle.c
@@ -1082,6 +1082,18 @@ demangle_path_maybe_open_generics (struct rust_demangler *rdm)
   if (rdm->errored)
     return open;
 
+  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.  */
+	  rdm->errored = 1;
+	  goto end_of_func;
+	}
+    }
+
   if (eat (rdm, 'B'))
     {
       backref = parse_integer_62 (rdm);
@@ -1107,6 +1119,11 @@ demangle_path_maybe_open_generics (struct rust_demangler *rdm)
     }
   else
     demangle_path (rdm, 0);
+
+ end_of_func:
+  if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
+    -- rdm->recursion;
+
   return open;
 }