Hi,
The attached patch fixes the stack overflow in the demangler due to cycles in
the references of “remembered” mangled types
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71696).
The methods demangle_signature and do_arg in cplus-dem.c allow to “remember”
mangled type names that can later be referenced and will also be demangled. The
method demangle_args demangles those types following any references. So, if
there is a cycle in the referencing (or in the simplest case a self-reference),
the method enters infinite recursion.
The patch tracks the mangled types that are currently being demangled in a new
variable called work->proctypevec. If a referenced type is currently being
demangled, the demangling is marked as not successful.
Bootstrapped and regression tested on x86_64-pc-linux-gnu. Test case added to
libiberty/testsuite/demangler-expected and checked PR71696 is resolved.
Index: libiberty/ChangeLog
===================================================================
--- libiberty/ChangeLog (revision 237852)
+++ libiberty/ChangeLog (working copy)
@@ -1,3 +1,21 @@
+2016-06-30 Marcel Böhme <boehme.mar...@gmail.com>
+
+ * cplus-dem.c: Prevent infinite recursion when there is a cycle
+ in the referencing of remembered mangled types.
+ (work_stuff): New stack to keep track of the remembered mangled
+ types that are currently being processed.
+ (push_processed_type): New method to push currently processed
+ remembered type onto the stack.
+ (pop_processed_type): New method to pop currently processed
+ remembered type from the stack.
+ (work_stuff_copy_to_from): Copy values of new variables.
+ (delete_non_B_K_work_stuff): Free stack memory.
+ (demangle_args): Push/Pop currently processed remembered type.
+ (do_type): Do not demangle a cyclic reference and push/pop
+ referenced remembered type.
+
+ * testsuite/demangle-expected: Add tests.
+
2016-05-31 Alan Modra <amo...@gmail.com>
* xmemdup.c (xmemdup): Use xmalloc rather than xcalloc.
Index: libiberty/cplus-dem.c
===================================================================
--- libiberty/cplus-dem.c (revision 237852)
+++ libiberty/cplus-dem.c (working copy)
@@ -144,6 +144,9 @@ struct work_stuff
string* previous_argument; /* The last function argument demangled. */
int nrepeats; /* The number of times to repeat the previous
argument. */
+ int *proctypevec; /* Indices of currently processed remembered typevecs.
*/
+ int proctypevec_size;
+ int nproctypes;
};
#define PRINT_ANSI_QUALIFIERS (work -> options & DMGL_ANSI)
@@ -436,6 +439,10 @@ iterate_demangle_function (struct work_stuff *,
static void remember_type (struct work_stuff *, const char *, int);
+static void push_processed_type (struct work_stuff *, int);
+
+static void pop_processed_type (struct work_stuff *);
+
static void remember_Btype (struct work_stuff *, const char *, int, int);
static int register_Btype (struct work_stuff *);
@@ -1302,6 +1309,13 @@ work_stuff_copy_to_from (struct work_stuff *to, st
memcpy (to->btypevec[i], from->btypevec[i], len);
}
+ if (from->proctypevec)
+ {
+ to->proctypevec = XNEWVEC (int, from->proctypevec_size);
+ memcpy (to->proctypevec, from->proctypevec,
+ from->proctypevec_size * sizeof(int));
+ }
+
if (from->ntmpl_args)
to->tmpl_argvec = XNEWVEC (char *, from->ntmpl_args);
@@ -1336,6 +1350,12 @@ delete_non_B_K_work_stuff (struct work_stuff *work
work -> typevec = NULL;
work -> typevec_size = 0;
}
+ if (work -> proctypevec != NULL)
+ {
+ free (work -> proctypevec);
+ work -> proctypevec = NULL;
+ work -> proctypevec_size = 0;
+ }
if (work->tmpl_argvec)
{
int i;
@@ -3554,6 +3574,8 @@ static int
do_type (struct work_stuff *work, const char **mangled, string *result)
{
int n;
+ int i;
+ int is_proctypevec;
int done;
int success;
string decl;
@@ -3566,6 +3588,7 @@ do_type (struct work_stuff *work, const char **man
done = 0;
success = 1;
+ is_proctypevec = 0;
while (success && !done)
{
int member;
@@ -3626,7 +3649,14 @@ do_type (struct work_stuff *work, const char **man
success = 0;
}
else
- {
+ for (i = 0; i < work -> nproctypes; i++)
+ if (work -> proctypevec [i] == n)
+ success = 0;
+
+ if (success)
+ {
+ is_proctypevec = 1;
+ push_processed_type (work, n);
remembered_type = work -> typevec[n];
mangled = &remembered_type;
}
@@ -3849,6 +3879,9 @@ do_type (struct work_stuff *work, const char **man
string_delete (result);
string_delete (&decl);
+ if (is_proctypevec)
+ pop_processed_type (work);
+
if (success)
/* Assume an integral type, if we're not sure. */
return (int) ((tk == tk_none) ? tk_integral : tk);
@@ -4261,6 +4294,34 @@ do_arg (struct work_stuff *work, const char **mang
}
static void
+push_processed_type (struct work_stuff *work, int typevec_index)
+{
+ if (work -> nproctypes >= work -> proctypevec_size)
+ {
+ if (work -> proctypevec_size == 0)
+ {
+ work -> proctypevec_size = 3;
+ work -> proctypevec = XNEWVEC (int, work -> proctypevec_size);
+ }
+ else
+ {
+ if (work -> proctypevec_size > INT_MAX / 2)
+ xmalloc_failed (INT_MAX);
+ work -> proctypevec_size *= 2;
+ work -> proctypevec
+ = XRESIZEVEC (int, work->proctypevec, work->proctypevec_size);
+ }
+ }
+ work -> proctypevec [work -> nproctypes ++] = typevec_index;
+}
+
+static void
+pop_processed_type (struct work_stuff *work)
+{
+ work -> nproctypes --;
+}
+
+static void
remember_type (struct work_stuff *work, const char *start, int len)
{
char *tem;
@@ -4524,10 +4585,13 @@ demangle_args (struct work_stuff *work, const char
{
string_append (declp, ", ");
}
+ push_processed_type (work, t);
if (!do_arg (work, &tem, &arg))
{
+ pop_processed_type (work);
return (0);
}
+ pop_processed_type (work);
if (PRINT_ARG_TYPES)
{
string_appends (declp, &arg);
Index: libiberty/testsuite/demangle-expected
===================================================================
--- libiberty/testsuite/demangle-expected (revision 237852)
+++ libiberty/testsuite/demangle-expected (working copy)
@@ -4556,3 +4556,8 @@ __vt_90000000000cafebabe
_Z80800000000000000000000
_Z80800000000000000000000
+#
+# Tests stack overflow PR71696
+
+__10%0__S4_0T0T0
+%0<>::%0(%0<>)
