On Wed, Apr 11, 2018 at 3:37 AM, H.J. Lu <hongjiu...@intel.com> wrote:
> When -fcf-protection -mcet is used, I got
>
> FAIL: g++.dg/eh/sighandle.C
>
> (gdb) bt
> #0 _Unwind_RaiseException (exc=exc@entry=0x416ed0)
> at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:140
> #1 0x00007ffff7d9936b in __cxxabiv1::__cxa_throw (obj=<optimized out>,
> tinfo=0x403dd0 <typeinfo for int@@CXXABI_1.3>, dest=0x0)
> at
> /export/gnu/import/git/sources/gcc/libstdc++-v3/libsupc++/eh_throw.cc:90
> #2 0x0000000000401255 in sighandler (signo=11, si=0x7fffffffd6f8,
> uc=0x7fffffffd5c0)
> at
> /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:9
> #3 <signal handler called> <<<< Signal frame which isn't on shadow stack
> #4 dosegv ()
> at
> /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:14
> #5 0x00000000004012e3 in main ()
> at
> /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:30
> (gdb) p frames
> $6 = 5
> (gdb)
>
> frame count should be 4, not 5. This patch skips signal frames when
> unwinding shadow stack.
>
> Tested on i686 and x86-64. OK for trunk?
>
> H.J.
> ----
> PR libgcc/85334
> * unwind-generic.h (_Unwind_Frames_Increment): New.
> * config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
> Likewise.
> * unwind.inc (_Unwind_RaiseException_Phase2): Increment frame
> count with _Unwind_Frames_Increment.
> (_Unwind_ForcedUnwind_Phase2): Likewise.
> ---
> libgcc/config/i386/shadow-stack-unwind.h | 5 +++++
> libgcc/unwind-generic.h | 3 +++
> libgcc/unwind.inc | 6 ++++--
> 3 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/libgcc/config/i386/shadow-stack-unwind.h
> b/libgcc/config/i386/shadow-stack-unwind.h
> index 40f48df2aec..a32f3e74b52 100644
> --- a/libgcc/config/i386/shadow-stack-unwind.h
> +++ b/libgcc/config/i386/shadow-stack-unwind.h
> @@ -49,3 +49,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.
> If not, see
> } \
> } \
> while (0)
> +
> +/* Increment frame count. Skip signal frames. */
> +#undef _Unwind_Frames_Increment
> +#define _Unwind_Frames_Increment(context, frames) \
> + if (!_Unwind_IsSignalFrame (context)) frames++
> diff --git a/libgcc/unwind-generic.h b/libgcc/unwind-generic.h
> index b5e3568e1bc..639c96f438e 100644
> --- a/libgcc/unwind-generic.h
> +++ b/libgcc/unwind-generic.h
> @@ -291,4 +291,7 @@ EXCEPTION_DISPOSITION _GCC_specific_handler
> (PEXCEPTION_RECORD, void *,
> /* Additional actions to unwind number of stack frames. */
> #define _Unwind_Frames_Extra(frames)
>
> +/* Increment frame count. */
> +#define _Unwind_Frames_Increment(context, frames) frames++
> +
> #endif /* unwind.h */
> diff --git a/libgcc/unwind.inc b/libgcc/unwind.inc
> index 68c08964d30..b49f8797009 100644
> --- a/libgcc/unwind.inc
> +++ b/libgcc/unwind.inc
> @@ -72,8 +72,9 @@ _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc,
> /* Don't let us unwind past the handler context. */
> gcc_assert (!match_handler);
>
> + _Unwind_Frames_Increment (context, frames);
> +
> uw_update_context (context, &fs);
> - frames++;
> }
>
> *frames_p = frames;
> @@ -187,10 +188,11 @@ _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception
> *exc,
> return _URC_FATAL_PHASE2_ERROR;
> }
>
> + _Unwind_Frames_Increment (context, frames);
> +
> /* Update cur_context to describe the same frame as fs, and discard
> the previous context if necessary. */
> uw_advance_context (context, &fs);
> - frames++;
> }
>
> *frames_p = frames;
> --
> 2.14.3
>
I need to increment frame count after uw_advance_context which will set
the signal frame bit.
OK for trunk?
--
H.J.
From 6ced07f8318d2c1faf616395b630c32c32e332f3 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.to...@gmail.com>
Date: Tue, 10 Apr 2018 20:46:04 -0700
Subject: [PATCH] libgcc/CET: Skip signal frames when unwinding shadow stack
When -fcf-protection -mcet is used, I got
FAIL: g++.dg/eh/sighandle.C
(gdb) bt
#0 _Unwind_RaiseException (exc=exc@entry=0x416ed0)
at /export/gnu/import/git/sources/gcc/libgcc/unwind.inc:140
#1 0x00007ffff7d9936b in __cxxabiv1::__cxa_throw (obj=<optimized out>,
tinfo=0x403dd0 <typeinfo for int@@CXXABI_1.3>, dest=0x0)
at /export/gnu/import/git/sources/gcc/libstdc++-v3/libsupc++/eh_throw.cc:90
#2 0x0000000000401255 in sighandler (signo=11, si=0x7fffffffd6f8,
uc=0x7fffffffd5c0)
at /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:9
#3 <signal handler called> <<<< Signal frame which isn't on shadow stack
#4 dosegv ()
at /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:14
#5 0x00000000004012e3 in main ()
at /export/gnu/import/git/sources/gcc/gcc/testsuite/g++.dg/eh/sighandle.C:30
(gdb) p frames
$6 = 5
(gdb)
frame count should be 4, not 5. This patch skips signal frames when
unwinding shadow stack.
gcc/testsuite/
PR libgcc/85334
* g++.dg/torture/pr85334.C: New test.
libgcc/
PR libgcc/85334
* unwind-generic.h (_Unwind_Frames_Increment): New.
* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
Likewise.
* unwind.inc (_Unwind_RaiseException_Phase2): Increment frame
count with _Unwind_Frames_Increment.
(_Unwind_ForcedUnwind_Phase2): Likewise.
---
gcc/testsuite/g++.dg/torture/pr85334.C | 40 ++++++++++++++++++++++++
libgcc/config/i386/shadow-stack-unwind.h | 5 +++
libgcc/unwind-generic.h | 3 ++
libgcc/unwind.inc | 4 +--
4 files changed, 50 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/torture/pr85334.C
diff --git a/gcc/testsuite/g++.dg/torture/pr85334.C b/gcc/testsuite/g++.dg/torture/pr85334.C
new file mode 100644
index 00000000000..7d0e2b7c465
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr85334.C
@@ -0,0 +1,40 @@
+// { dg-do run { target { i?86-*-linux* i?86-*-gnu* x86_64-*-linux* } } }
+// { dg-require-effective-target cet }
+// { dg-options "-fexceptions -fnon-call-exceptions -O2 -fcf-protection -mcet" }
+
+#include <signal.h>
+#include <stdlib.h>
+
+void sighandler (int signo, siginfo_t * si, void * uc)
+{
+ throw (5);
+}
+
+char * dosegv ()
+{
+ * ((volatile int *)0) = 12;
+ return 0;
+}
+
+int main ()
+{
+ struct sigaction sa;
+ int status;
+
+ sa.sa_sigaction = sighandler;
+ sa.sa_flags = SA_SIGINFO;
+
+ status = sigaction (SIGSEGV, & sa, NULL);
+ status = sigaction (SIGBUS, & sa, NULL);
+
+ try {
+ dosegv ();
+ }
+ catch (int x) {
+ return (x != 5);
+ }
+
+ return 1;
+}
+
+
diff --git a/libgcc/config/i386/shadow-stack-unwind.h b/libgcc/config/i386/shadow-stack-unwind.h
index 40f48df2aec..a32f3e74b52 100644
--- a/libgcc/config/i386/shadow-stack-unwind.h
+++ b/libgcc/config/i386/shadow-stack-unwind.h
@@ -49,3 +49,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
} \
} \
while (0)
+
+/* Increment frame count. Skip signal frames. */
+#undef _Unwind_Frames_Increment
+#define _Unwind_Frames_Increment(context, frames) \
+ if (!_Unwind_IsSignalFrame (context)) frames++
diff --git a/libgcc/unwind-generic.h b/libgcc/unwind-generic.h
index b5e3568e1bc..639c96f438e 100644
--- a/libgcc/unwind-generic.h
+++ b/libgcc/unwind-generic.h
@@ -291,4 +291,7 @@ EXCEPTION_DISPOSITION _GCC_specific_handler (PEXCEPTION_RECORD, void *,
/* Additional actions to unwind number of stack frames. */
#define _Unwind_Frames_Extra(frames)
+/* Increment frame count. */
+#define _Unwind_Frames_Increment(context, frames) frames++
+
#endif /* unwind.h */
diff --git a/libgcc/unwind.inc b/libgcc/unwind.inc
index 68c08964d30..19a8e4f6c80 100644
--- a/libgcc/unwind.inc
+++ b/libgcc/unwind.inc
@@ -73,7 +73,7 @@ _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc,
gcc_assert (!match_handler);
uw_update_context (context, &fs);
- frames++;
+ _Unwind_Frames_Increment (context, frames);
}
*frames_p = frames;
@@ -190,7 +190,7 @@ _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc,
/* Update cur_context to describe the same frame as fs, and discard
the previous context if necessary. */
uw_advance_context (context, &fs);
- frames++;
+ _Unwind_Frames_Increment (context, frames);
}
*frames_p = frames;
--
2.17.0
