On Sat, Jan 13, 2024 at 5:10 PM Julia DeMille <m...@jdemille.com> wrote:
>
> Currently, when std::terminate() is called with a foreign exception
> active, since nothing in the path checks whether the exception matches
> the `GNUCC++\0` personality, a foreign exception can go into the verbose
> terminate handler, and get treated as though it were a C++ exception.
>
> Reflection is attempted, and boom. UB. This patch should eliminate that
> UB.
2 things, changelogs go into the email message rather than directly as
part of the patch.,
Second I wonder if you could add a multiple language testcase using
GNU objective-C exceptions as an example.
If not directly adding a testcase there, at least a simple test that
shows the issue outside of the testsuite?
Thanks,
Andrew Pinski
>
> Signed-off-by: Julia DeMille <m...@jdemille.com>
> ---
> libstdc++-v3/ChangeLog | 9 +++++++++
> libstdc++-v3/libsupc++/eh_type.cc | 11 +++++++++++
> libstdc++-v3/libsupc++/vterminate.cc | 25 ++++++++++++++++++++-----
> 3 files changed, 40 insertions(+), 5 deletions(-)
>
> diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
> index 36257cc4427..bfef0ed8ef1 100644
> --- a/libstdc++-v3/ChangeLog
> +++ b/libstdc++-v3/ChangeLog
> @@ -1,3 +1,12 @@
> +2024-01-13 Julia DeMille <m...@jdemille.com>
> + * libsupc++/eh_type.cc (__cxa_current_exception_type):
> + Return NULL if the current exception is not the `GNUCC++\0`
> + personality.
> + * libsupc++/vterminate.cc:
> + Check for both exception header and exception type. If there
> + is an exception header, but no exception type, state in termination
> + message that a foreign exception was active.
> +
> 2024-01-13 Jonathan Wakely <jwak...@redhat.com>
>
> PR libstdc++/107466
> diff --git a/libstdc++-v3/libsupc++/eh_type.cc
> b/libstdc++-v3/libsupc++/eh_type.cc
> index 03c677b7e13..e0824eab4d4 100644
> --- a/libstdc++-v3/libsupc++/eh_type.cc
> +++ b/libstdc++-v3/libsupc++/eh_type.cc
> @@ -36,9 +36,20 @@ extern "C"
> std::type_info *__cxa_current_exception_type () _GLIBCXX_NOTHROW
> {
> __cxa_eh_globals *globals = __cxa_get_globals ();
> +
> + if (!globals)
> + return 0;
> +
> __cxa_exception *header = globals->caughtExceptions;
> +
> if (header)
> {
> + // It is UB to try and inspect an exception that isn't ours.
> + // This extends to attempting to perform run-time reflection, as the
> ABI
> + // is unknown.
> + if (!__is_gxx_exception_class (header->unwindHeader.exception_class))
> + return 0;
> +
> if (__is_dependent_exception (header->unwindHeader.exception_class))
> {
> __cxa_dependent_exception *de =
> diff --git a/libstdc++-v3/libsupc++/vterminate.cc
> b/libstdc++-v3/libsupc++/vterminate.cc
> index 23deeef5289..f931d951526 100644
> --- a/libstdc++-v3/libsupc++/vterminate.cc
> +++ b/libstdc++-v3/libsupc++/vterminate.cc
> @@ -25,11 +25,12 @@
> #include <bits/c++config.h>
>
> #if _GLIBCXX_HOSTED
> -#include <cstdlib>
> -#include <exception>
> +#include "unwind-cxx.h"
> #include <bits/exception_defines.h>
> +#include <cstdio>
> +#include <cstdlib>
> #include <cxxabi.h>
> -# include <cstdio>
> +#include <exception>
>
> using namespace std;
> using namespace abi;
> @@ -51,10 +52,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> terminating = true;
>
> + __cxa_eh_globals *globals = __cxa_get_globals ();
> + if (!globals)
> + {
> + fputs ("terminate called", stderr);
> + abort ();
> + }
> +
> // Make sure there was an exception; terminate is also called for an
> // attempt to rethrow when there is no suitable exception.
> - type_info *t = __cxa_current_exception_type();
> - if (t)
> + type_info *t = __cxa_current_exception_type ();
> + __cxa_exception *header = globals->caughtExceptions;
> +
> + if (t && header)
> {
> // Note that "name" is the mangled name.
> char const *name = t->name();
> @@ -89,6 +99,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif
> __catch(...) { }
> }
> + else if (header)
> + {
> + fputs ("terminate called after a foreign exception was thrown\n",
> + stderr);
> + }
> else
> fputs("terminate called without an active exception\n", stderr);
>
> --
> 2.43.0
>
