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libgcc/CET: Skip signal frames when unwinding shadow stack

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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.

From-SVN: r259502
This commit is contained in:
H.J. Lu 2018-04-19 17:05:39 +00:00 committed by H.J. Lu
parent f22723f93d
commit 5707be3c7d
6 changed files with 63 additions and 2 deletions
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5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2018-04-19 H.J. Lu <hongjiu.lu@intel.com>
PR libgcc/85334
* g++.dg/torture/pr85334.C: New test.
2018-04-19 Jonathan Wakely <jwakely@redhat.com>
PR c++/85464 - missing location for -Wignored-qualifiers diagnostic

38
gcc/testsuite/g++.dg/torture/pr85334.C Normal file
View File

@ -0,0 +1,38 @@
// { dg-do run { target { i?86-*-linux* i?86-*-gnu* x86_64-*-linux* } } }
// { dg-require-effective-target cet }
// { dg-additional-options "-fexceptions -fnon-call-exceptions -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;
}

10
libgcc/ChangeLog
View File

@ -1,3 +1,13 @@
2018-04-19 H.J. Lu <hongjiu.lu@intel.com>
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.
2018-04-19 H.J. Lu <hongjiu.lu@intel.com>
PR libgcc/85379

5
libgcc/config/i386/shadow-stack-unwind.h
View File

@ -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++

3
libgcc/unwind-generic.h
View File

@ -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 */

4
libgcc/unwind.inc
View File

@ -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;