From 5707be3c7da6196efcef2d86e623771153eb6c7f Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 19 Apr 2018 17:05:39 +0000 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=, tinfo=0x403dd0 , 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 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 --- gcc/testsuite/ChangeLog | 5 ++++ gcc/testsuite/g++.dg/torture/pr85334.C | 38 ++++++++++++++++++++++++ libgcc/ChangeLog | 10 +++++++ libgcc/config/i386/shadow-stack-unwind.h | 5 ++++ libgcc/unwind-generic.h | 3 ++ libgcc/unwind.inc | 4 +-- 6 files changed, 63 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/torture/pr85334.C diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 62dec374218..e7b9547c1a4 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2018-04-19 H.J. Lu + + PR libgcc/85334 + * g++.dg/torture/pr85334.C: New test. + 2018-04-19 Jonathan Wakely PR c++/85464 - missing location for -Wignored-qualifiers diagnostic diff --git a/gcc/testsuite/g++.dg/torture/pr85334.C b/gcc/testsuite/g++.dg/torture/pr85334.C new file mode 100644 index 00000000000..080978143bd --- /dev/null +++ b/gcc/testsuite/g++.dg/torture/pr85334.C @@ -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 +#include + +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/ChangeLog b/libgcc/ChangeLog index 674d2041bd7..8a645c80e3d 100644 --- a/libgcc/ChangeLog +++ b/libgcc/ChangeLog @@ -1,3 +1,13 @@ +2018-04-19 H.J. Lu + + 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 PR libgcc/85379 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; -- 2.30.2