On Wed, Sep 16, 2020 at 11:22:02AM -0700, Nick Desaulniers wrote:
> I looked into this a bit, and IIRC, the issue was that compiler
> generated functions aren't very good about keeping track of whether
> they should or should not emit framepointer setup/teardown
> prolog/epilogs. In LLVM's IR, -fn
> On 17 Sep 2020, at 13:04, Mark Rutland wrote:
>
> On Wed, Sep 16, 2020 at 10:30:42PM +0100, Daniel Kiss wrote:
>>
>>Thanks for the summary -- yeah, that was my suspicion, that some
>>attribute was being lost somewhere. And I think if we generalize this,
>>and don't just try to atta
On Wed, Sep 16, 2020 at 10:30:42PM +0100, Daniel Kiss wrote:
>
> Thanks for the summary -- yeah, that was my suspicion, that some
> attribute was being lost somewhere. And I think if we generalize this,
> and don't just try to attach "frame-pointer" attr to the function, we
> proba
On 2020-09-16, 'Marco Elver' via Clang Built Linux wrote:
On Wed, 16 Sep 2020 at 20:22, 'Nick Desaulniers' via kasan-dev
wrote:
On Wed, Sep 16, 2020 at 1:46 AM Marco Elver wrote:
>
> On Wed, 16 Sep 2020 at 10:30, wrote:
> > On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> > > O
On Tue, Sep 15, 2020 at 05:50:54PM -0400, Arvind Sankar wrote:
> On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> >
> > (Btw, clang doesn't need to add that "xor %eax,%eax" - panic() should not be
> > returning, ever. :-))
> >
>
> I think this is because panic() is varargs, an
On Wed, 16 Sep 2020 at 20:22, 'Nick Desaulniers' via kasan-dev
wrote:
>
> On Wed, Sep 16, 2020 at 1:46 AM Marco Elver wrote:
> >
> > On Wed, 16 Sep 2020 at 10:30, wrote:
> > > On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> > > > On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers
> >
On Wed, Sep 16, 2020 at 1:46 AM Marco Elver wrote:
>
> On Wed, 16 Sep 2020 at 10:30, wrote:
> > On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> > > On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers
> > > wrote:
> > > > On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote:
> >
> >
On Wed, Sep 16, 2020 at 11:28:26AM -0700, Nick Desaulniers wrote:
> pt. 3
> https://nickdesaulniers.github.io/blog/2014/04/18/lets-write-some-x86-64/
/me adds to the read list.
> ...2014, jesus...
>
> "But you never can tell exactly what the compiler is doing. It doesn’t
> always come out the w
On Wed, Sep 16, 2020 at 4:34 AM Borislav Petkov wrote:
>
> On Tue, Sep 15, 2020 at 05:50:54PM -0400, Arvind Sankar wrote:
> > On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> > >
> > > (Btw, clang doesn't need to add that "xor %eax,%eax" - panic() should not
> > > be
> > > retu
On Wed, 16 Sep 2020 at 11:06, wrote:
> On Wed, Sep 16, 2020 at 10:46:41AM +0200, Marco Elver wrote:
> > On Wed, 16 Sep 2020 at 10:30, wrote:
> > > On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> > > > On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers
> > > > wrote:
> > > > > On Tue,
On Wed, Sep 16, 2020 at 10:46:41AM +0200, Marco Elver wrote:
> On Wed, 16 Sep 2020 at 10:30, wrote:
> > On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> > > On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers
> > > wrote:
> > > > On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote:
On Wed, 16 Sep 2020 at 00:34, Nick Desaulniers wrote:
> On Tue, Sep 15, 2020 at 2:02 PM Josh Poimboeuf wrote:
> >
> > panic() is noreturn, so the compiler is enforcing the fact that it
> > doesn't return, by trapping if it does return.
> >
> > I seem to remember that's caused by CONFIG_UBSAN_TRAP
On Wed, 16 Sep 2020 at 10:30, wrote:
> On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> > On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers
> > wrote:
> > > On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote:
>
> > > > init/calibrate.o: warning: objtool: asan.module_ctor()+0xc: c
On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote:
> On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers
> wrote:
> > On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote:
> > > init/calibrate.o: warning: objtool: asan.module_ctor()+0xc: call without
> > > frame pointer save/setup
> > >
> Should objtool be made aware of the config option and then not check
> traps after no-returns?
>
> I suspect the latter, but I'm not sure how feasible it is to
> implement. Josh, Marco, do you have thoughts on the above?
This seems to do the trick.
diff --git a/tools/objtool/check.c b/tools/ob
tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
x86/seves
branch HEAD: e6eb15c9ba3165698488ae5c34920eea20eaa38e KVM: nSVM: Avoid freeing
uninitialized pointers in svm_set_nested_state()
Warning in current branch:
arch/x86/kernel/sev-es.o: warning: objtool: ist_ex
On Tue, Sep 15, 2020 at 09:42:56PM +0800, kernel test robot wrote:
> tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
> x86/seves
> branch HEAD: e6eb15c9ba3165698488ae5c34920eea20eaa38e KVM: nSVM: Avoid
> freeing uninitialized pointers in svm_set_nested_state()
>
>
On Tue, 15 Sep 2020 at 23:28, Josh Poimboeuf wrote:
> On Tue, Sep 15, 2020 at 02:13:01PM -0700, Nick Desaulniers wrote:
> > Triple checking what I wrote above; it looks like the randconfig had
> > BOTH CONFIG_KASAN=y and CONFIG_UBSAN=y enabled. Aren't the sanitizers
> > supposed to be mutually ex
On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote:
> I attached the config for your reference.
Thanks.
Can you pls fix your reporting so that the mail has the .config
attached?
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Tue, Sep 15, 2020 at 02:59:19PM -0700, Nick Desaulniers wrote:
> On Tue, Sep 15, 2020 at 2:50 PM Arvind Sankar wrote:
> >
> > On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> > >
> > > (Btw, clang doesn't need to add that "xor %eax,%eax" - panic() should not
> > > be
> > > r
On Tue, Sep 15, 2020 at 2:02 PM Josh Poimboeuf wrote:
>
> panic() is noreturn, so the compiler is enforcing the fact that it
> doesn't return, by trapping if it does return.
>
> I seem to remember that's caused by CONFIG_UBSAN_TRAP.
Indeed, if I remove CONFIG_UBSAN_TRAP from the 0day report's
ran
On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote:
> On Tue, Sep 15, 2020 at 03:55:19PM +0200, Borislav Petkov wrote:
> > On Tue, Sep 15, 2020 at 09:42:56PM +0800, kernel test robot wrote:
> > > tree/branch:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
> > > x86
On Tue, Sep 15, 2020 at 1:12 PM Nick Desaulniers
wrote:
>
> On Tue, Sep 15, 2020 at 10:02 AM Josh Poimboeuf wrote:
> >
> > On Tue, Sep 15, 2020 at 06:05:54PM +0200, Borislav Petkov wrote:
> > > On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote:
> > > > On Tue, Sep 15, 2020 at 03:55:19PM +
On Tue, Sep 15, 2020 at 2:50 PM Arvind Sankar wrote:
>
> On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> >
> > (Btw, clang doesn't need to add that "xor %eax,%eax" - panic() should not be
> > returning, ever. :-))
> >
>
> I think this is because panic() is varargs, and clang do
On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
>
> (Btw, clang doesn't need to add that "xor %eax,%eax" - panic() should not be
> returning, ever. :-))
>
I think this is because panic() is varargs, and clang doesn't support
gcc's -mskip-rax-setup. The normal ABI requires the c
On Tue, Sep 15, 2020 at 02:13:01PM -0700, Nick Desaulniers wrote:
> Triple checking what I wrote above; it looks like the randconfig had
> BOTH CONFIG_KASAN=y and CONFIG_UBSAN=y enabled. Aren't the sanitizers
> supposed to be mutually exclusive? If so, we should ensure that via
> kconfig these ca
On Tue, Sep 15, 2020 at 04:02:31PM -0500, Josh Poimboeuf wrote:
> panic() is noreturn, so the compiler is enforcing the fact that it
> doesn't return, by trapping if it does return.
>
> I seem to remember that's caused by CONFIG_UBSAN_TRAP.
>From IRC: yah, CONFIG_UBSAN_TRAP=y in that config. But
On Tue, Sep 15, 2020 at 10:49:12PM +0200, Borislav Petkov wrote:
> On Tue, Sep 15, 2020 at 01:12:24PM -0700, Nick Desaulniers wrote:
> > 1 warning: objtool: ist_exc_vmm_communication()+0x12: unreachable
> > instruction
>
> That looks interesting. So your .o has:
>
> 04c0 :
> 4
On Tue, Sep 15, 2020 at 01:12:24PM -0700, Nick Desaulniers wrote:
> 1 warning: objtool: ist_exc_vmm_communication()+0x12: unreachable
> instruction
That looks interesting. So your .o has:
04c0 :
4c0: 55 push %rbp
4c1: 48 89 e5mov
On Tue, Sep 15, 2020 at 10:02 AM Josh Poimboeuf wrote:
>
> On Tue, Sep 15, 2020 at 06:05:54PM +0200, Borislav Petkov wrote:
> > On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote:
> > > On Tue, Sep 15, 2020 at 03:55:19PM +0200, Borislav Petkov wrote:
> > > > On Tue, Sep 15, 2020 at 09:42:56
On Tue, Sep 15, 2020 at 06:05:54PM +0200, Borislav Petkov wrote:
> On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote:
> > On Tue, Sep 15, 2020 at 03:55:19PM +0200, Borislav Petkov wrote:
> > > On Tue, Sep 15, 2020 at 09:42:56PM +0800, kernel test robot wrote:
> > > > tree/branch:
> > > > h
On Tue, Sep 15, 2020 at 12:02:48PM -0500, Josh Poimboeuf wrote:
> If somebody can share the .o file, I can take a look.
If only I could reproduce...
So I built:
/home/share/src/llvm/tc-build/install/bin/clang-12 --version
ClangBuiltLinux clang version 12.0.0 (https://github.com/llvm/llvm-project
On Tue, Sep 15, 2020 at 10:41:24AM -0700, Nick Desaulniers wrote:
> We want them finding bugs in unreleased versions of the compiler,
> before those bugs in ship in release. This is a good thing.
The bug report should probably say that compiler used is an unreleased
one so that I can prioritize b
On Tue, Sep 15, 2020 at 11:01 AM Borislav Petkov wrote:
>
> On Tue, Sep 15, 2020 at 10:41:24AM -0700, Nick Desaulniers wrote:
> > We want them finding bugs in unreleased versions of the compiler,
> > before those bugs in ship in release. This is a good thing.
>
> The bug report should probably sa
On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers wrote:
>
> On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote:
> >
> > On Tue, Sep 15, 2020 at 12:02:48PM -0500, Josh Poimboeuf wrote:
> > > If somebody can share the .o file, I can take a look.
> >
> > If only I could reproduce...
> >
> > So I b
On Tue, Sep 15, 2020 at 10:02 AM Josh Poimboeuf wrote:
>
> On Tue, Sep 15, 2020 at 06:05:54PM +0200, Borislav Petkov wrote:
> > On Tue, Sep 15, 2020 at 10:18:16PM +0800, Rong Chen wrote:
> > > On Tue, Sep 15, 2020 at 03:55:19PM +0200, Borislav Petkov wrote:
> > > > On Tue, Sep 15, 2020 at 09:42:56
On Tue, Sep 15, 2020 at 10:34 AM Borislav Petkov wrote:
>
> On Tue, Sep 15, 2020 at 07:21:52PM +0200, Borislav Petkov wrote:
> > I'm thinking clang12 is too unstable to take it seriously...
>
> Yeah, I'm being told v12 is not even close to getting released. So why
> are you 0day guys testing with
On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote:
>
> On Tue, Sep 15, 2020 at 12:02:48PM -0500, Josh Poimboeuf wrote:
> > If somebody can share the .o file, I can take a look.
>
> If only I could reproduce...
>
> So I built:
>
> /home/share/src/llvm/tc-build/install/bin/clang-12 --version
>
On Tue, Sep 15, 2020 at 07:21:52PM +0200, Borislav Petkov wrote:
> I'm thinking clang12 is too unstable to take it seriously...
Yeah, I'm being told v12 is not even close to getting released. So why
are you 0day guys testing with it and reporting issues? Are you testing
unreleased compilers and re
On Tue, Sep 15, 2020 at 03:55:19PM +0200, Borislav Petkov wrote:
> On Tue, Sep 15, 2020 at 09:42:56PM +0800, kernel test robot wrote:
> > tree/branch:
> > https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/seves
> > branch HEAD: e6eb15c9ba3165698488ae5c34920eea20eaa38e KVM: nSV
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