diff mbox series

RFA: Libiberty: Fix stack exhaunstion demangling corrupt rust names

Message ID d72930a5-9efe-8278-8e07-1d3bb61fe0d2@redhat.com
State New
Headers show
Series RFA: Libiberty: Fix stack exhaunstion demangling corrupt rust names | expand

Commit Message

Nick Clifton July 15, 2021, 2:59 p.m. UTC 
Hi Guys,

   Attached is a proposed patch to fix PR 99935 and 100968, both
   of which are stack exhaustion problems in libiberty's Rust
   demangler.  The patch adds a recursion limit along the lines
   of the one already in place for the C++ demangler.

   OK to apply ?

Cheers
   Nick
diff mbox series

Patch

diff --git a/libiberty/rust-demangle.c b/libiberty/rust-demangle.c
index 6fd8f6a4db0..df09b7b8fdd 100644
--- a/libiberty/rust-demangle.c
+++ b/libiberty/rust-demangle.c
@@ -74,6 +74,12 @@  struct rust_demangler
   /* Rust mangling version, with legacy mangling being -1. */
   int version;
 
+  /* Recursion depth.  */
+  uint recursion;
+  /* Maximum number of times demangle_path may be called recursively.  */
+#define RUST_MAX_RECURSION_COUNT  1024
+#define RUST_NO_RECURSION_LIMIT   ((uint) -1)
+
   uint64_t bound_lifetime_depth;
 };
 
@@ -671,6 +677,15 @@  demangle_path (struct rust_demangler *rdm, int in_value)
   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;
+    }
+
   switch (tag = next (rdm))
     {
     case 'C':
@@ -688,10 +703,7 @@  demangle_path (struct rust_demangler *rdm, int in_value)
     case 'N':
       ns = next (rdm);
       if (!ISLOWER (ns) && !ISUPPER (ns))
-        {
-          rdm->errored = 1;
-          return;
-        }
+	goto fail_return;
 
       demangle_path (rdm, in_value);
 
@@ -776,9 +788,15 @@  demangle_path (struct rust_demangler *rdm, int in_value)
         }
       break;
     default:
-      rdm->errored = 1;
-      return;
+      goto fail_return;
     }
+  goto pass_return;
+
+ fail_return:
+  rdm->errored = 1;
+ pass_return:
+  if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
+    -- rdm->recursion;
 }
 
 static void
@@ -1317,6 +1338,7 @@  rust_demangle_callback (const char *mangled, int options,
   rdm.skipping_printing = 0;
   rdm.verbose = (options & DMGL_VERBOSE) != 0;
   rdm.version = 0;
+  rdm.recursion = (options & DMGL_NO_RECURSE_LIMIT) ? RUST_NO_RECURSION_LIMIT : 0;
   rdm.bound_lifetime_depth = 0;
 
   /* Rust symbols always start with _R (v0) or _ZN (legacy). */