demangler, only access valid fields for DEMANGLE_COMPONENT_FIXED_TYPE.
Commit Message
In two places when a struct demangle_component is of type
DEMANGLE_COMPONENT_FIXED_TYPE we fall back to accessing the default
s_binary member of the union rather than the s_fixed member. This is
incorrect and can cause the demangler to crash.
In d_dump I've changed the code to only access the s_fixed member of the
union, and also added printing of the remaining parts of the s_fixed
struct, this felt like the most useful thing to do.
I've added a new test, this causes a SIGSEGV for me before the patch, and
is fine afterwords, however, this undefined, so might not cause a crash on
all platforms.
If this is approved then please could someone commit it for me, I don't
have gcc write access.
Thanks,
Andrew
libiberty/ChangeLog:
* cp-demangle.c (d_dump): Only access field from s_fixed part of
the union for DEMANGLE_COMPONENT_FIXED_TYPE.
(d_count_templates_scopes): Likewise.
* testsuite/demangle-expected: New test case.
---
libiberty/cp-demangle.c | 10 +++++++++-
libiberty/testsuite/demangle-expected | 6 ++++++
2 files changed, 15 insertions(+), 1 deletion(-)
Comments
On 05/28/2014 09:38 PM, Andrew Burgess wrote:
> In two places when a struct demangle_component is of type
> DEMANGLE_COMPONENT_FIXED_TYPE we fall back to accessing the default
> s_binary member of the union rather than the s_fixed member. This is
> incorrect and can cause the demangler to crash.
>
> In d_dump I've changed the code to only access the s_fixed member of the
> union, and also added printing of the remaining parts of the s_fixed
> struct, this felt like the most useful thing to do.
>
> I've added a new test, this causes a SIGSEGV for me before the patch, and
> is fine afterwords, however, this undefined, so might not cause a crash on
> all platforms.
Hi Andrew,
As you know, I'm not a demangler maintainer, but in any case, I took a look
and this looks good to me.
> diff --git a/libiberty/testsuite/demangle-expected b/libiberty/testsuite/demangle-expected
> index 453f9a3..0e2bb12 100644
> --- a/libiberty/testsuite/demangle-expected
> +++ b/libiberty/testsuite/demangle-expected
> @@ -4343,3 +4343,9 @@ cereal::detail::InputBindingMap<cereal::JSONInputArchive>::Serializers cereal::p
> --format=gnu-v3
> _ZNSt9_Any_data9_M_accessIPZ4postISt8functionIFvvEEEvOT_EUlvE_EERS5_v
> void post<std::function<void ()> >(std::function<void ()>&&)::{lambda()#1}*& std::_Any_data::_M_access<void post<std::function<void ()> >(void post<std::function<void ()> >(std::function<void ()>&&)::{lambda()#1}*&&)::{lambda()#1}*>()
> +# The following input symbol was found during random, it caused a fault
Could you add a single empty # above, to separate the tests?
I find that that makes it much easier to follow the file.
I have no idea why we can't have/handle real empty lines though.
> +# The following input symbol was found during random, it caused a fault
"during random testing?"
> +# within the demangler, it's not a symbol we'd expect in the real world.
Why not?
> +--format=auto --no-params
> +_Z3xxxDFyuVb
> +xxx(unsigned long long _Fract, bool volatile)
> +xxx
@@ -710,7 +710,9 @@ d_dump (struct demangle_component *dc, int indent)
printf ("pointer to member type\n");
break;
case DEMANGLE_COMPONENT_FIXED_TYPE:
- printf ("fixed-point type\n");
+ printf ("fixed-point type, accum? %d, sat? %d\n",
+ dc->u.s_fixed.accum, dc->u.s_fixed.sat);
+ d_dump (dc->u.s_fixed.length, indent + 2)
break;
case DEMANGLE_COMPONENT_ARGLIST:
printf ("argument list\n");
@@ -3869,7 +3871,13 @@ d_count_templates_scopes (int *num_templates, int *num_scopes,
case DEMANGLE_COMPONENT_FUNCTION_TYPE:
case DEMANGLE_COMPONENT_ARRAY_TYPE:
case DEMANGLE_COMPONENT_PTRMEM_TYPE:
+ goto recurse_left_right;
+
case DEMANGLE_COMPONENT_FIXED_TYPE:
+ d_count_templates_scopes (num_templates, num_scopes,
+ dc->u.s_fixed.length);
+ break;
+
case DEMANGLE_COMPONENT_VECTOR_TYPE:
case DEMANGLE_COMPONENT_ARGLIST:
case DEMANGLE_COMPONENT_TEMPLATE_ARGLIST:
@@ -4343,3 +4343,9 @@ cereal::detail::InputBindingMap<cereal::JSONInputArchive>::Serializers cereal::p
--format=gnu-v3
_ZNSt9_Any_data9_M_accessIPZ4postISt8functionIFvvEEEvOT_EUlvE_EERS5_v
void post<std::function<void ()> >(std::function<void ()>&&)::{lambda()#1}*& std::_Any_data::_M_access<void post<std::function<void ()> >(void post<std::function<void ()> >(std::function<void ()>&&)::{lambda()#1}*&&)::{lambda()#1}*>()
+# The following input symbol was found during random, it caused a fault
+# within the demangler, it's not a symbol we'd expect in the real world.
+--format=auto --no-params
+_Z3xxxDFyuVb
+xxx(unsigned long long _Fract, bool volatile)
+xxx