Hi Ian,
>>> Shouldn't we make it fool-proof by instead introducing a
>>> DMGL_NO_RECURSION_LIMIT
> You don't need my blessing--I wrote that code ages ago--but I agree
> with Richard that in practice it's OK to limit recursion depth by
> default. Real symbols have very limited recursion requirements.
OK then, here is a fourth revision of the patch.
In this version:
* The demangler option has been renamed to DMGHL_NO_RECURSE_LIMIT
and if the option is not present then the limit is enforced.
* I also found another PR that is fixed by the patch, although I had
to make sure that the affected code could handle NULL pointers
properly afterwards.
OK to apply ?
Cheers
Nick
include/ChangeLog
2018-11-29 Nick Clifton
* demangle.h (DMGL_NO_RECURSE_LIMIT): Define.
(DEMANGLE_RECURSION_LIMIT): Define
libiberty/ChangeLog
2018-11-29 Nick Clifton
PR 87681
PR 87675
PR 87636
PR 87350
PR 87335
* cp-demangle.h (struct d_info): Add recursion_level field.
* cp-demangle.c (d_function_type): Add recursion counter.
If the recursion limit is reached and the check is not disabled,
then return with a failure result.
(cplus_demangle_init_info): Initialise the recursion_level field.
(d_demangle_callback): If the recursion limit is enabled, check
for a mangled string that is so long that there is not enough
stack space for the local arrays.
* cplus-dem.c (struct work): Add recursion_level field.
(squangle_mop_up): Set the numb and numk fields to zero.
(work_stuff_copy_to_from): Handle the case where a btypevec or
ktypevec field is NULL.
(demangle_nested_args): Add recursion counter. If
the recursion limit is not disabled and reached, return with a
failure result.
Index: include/demangle.h
===
--- include/demangle.h (revision 266771)
+++ include/demangle.h (working copy)
@@ -68,6 +68,17 @@
/* If none of these are set, use 'current_demangling_style' as the default. */
#define DMGL_STYLE_MASK (DMGL_AUTO|DMGL_GNU|DMGL_LUCID|DMGL_ARM|DMGL_HP|DMGL_EDG|DMGL_GNU_V3|DMGL_JAVA|DMGL_GNAT|DMGL_DLANG|DMGL_RUST)
+/* Disable a limit on the depth of recursion in mangled strings.
+ Note if this limit is disabled then stack exhaustion is possible when
+ demangling pathologically complicated strings. Bug reports about stack
+ exhaustion when the option is enabled will be rejected. */
+#define DMGL_NO_RECURSE_LIMIT (1 << 18)
+
+/* If DMGL_NO_RECURE_LIMIT is not enabled, then this is the value used as
+ the maximum depth of recursion allowed. It should be enough for any
+ real-world mangled name. */
+#define DEMANGLE_RECURSION_LIMIT 1024
+
/* Enumeration of possible demangling styles.
Lucid and ARM styles are still kept logically distinct, even though
Index: libiberty/cp-demangle.c
===
--- libiberty/cp-demangle.c (revision 266771)
+++ libiberty/cp-demangle.c (working copy)
@@ -2852,21 +2852,35 @@
static struct demangle_component *
d_function_type (struct d_info *di)
{
- struct demangle_component *ret;
+ struct demangle_component *ret = NULL;
- if (! d_check_char (di, 'F'))
-return NULL;
- if (d_peek_char (di) == 'Y')
+ if ((di->options & DMGL_NO_RECURSE_LIMIT) == 0)
{
- /* Function has C linkage. We don't print this information.
- FIXME: We should print it in verbose mode. */
- d_advance (di, 1);
+ if (di->recursion_level > DEMANGLE_RECURSION_LIMIT)
+ /* FIXME: There ought to be a way to report
+ that the recursion limit has been reached. */
+ return NULL;
+
+ di->recursion_level ++;
}
- ret = d_bare_function_type (di, 1);
- ret = d_ref_qualifier (di, ret);
- if (! d_check_char (di, 'E'))
-return NULL;
+ if (d_check_char (di, 'F'))
+{
+ if (d_peek_char (di) == 'Y')
+ {
+ /* Function has C linkage. We don't print this information.
+ FIXME: We should print it in verbose mode. */
+ d_advance (di, 1);
+ }
+ ret = d_bare_function_type (di, 1);
+ ret = d_ref_qualifier (di, ret);
+
+ if (! d_check_char (di, 'E'))
+ ret = NULL;
+}
+
+ if ((di->options & DMGL_NO_RECURSE_LIMIT) == 0)
+di->recursion_level --;
return ret;
}
@@ -6203,6 +6217,7 @@
di->expansion = 0;
di->is_expression = 0;
di->is_conversion = 0;
+ di->recursion_level = 0;
}
/* Internal implementation for the demangler. If MANGLED is a g++ v3 ABI
@@ -6242,6 +6257,20 @@
cplus_demangle_init_info (mangled, options, strlen (mangled), );
+ /* PR 87675 - Check for a mangled string that is so long
+ that we do not have enough stack space to demangle it. */
+ if (((options & DMGL_NO_RECURSE_LIMIT) == 0)
+ /* This check is a bit arbitrary, since what we really want to do is to
+ compare the sizes
