From: George Popescu <georgepope@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: maz@kernel.org, catalin.marinas@arm.com, will@kernel.org,
masahiroy@kernel.org, michal.lkml@markovi.net,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com,
james.morse@arm.com, julien.thierry.kdev@gmail.com,
suzuki.poulose@arm.com, natechancellor@gmail.com,
ndesaulniers@google.com, dbrazdil@google.com, broonie@kernel.org,
maskray@google.com, ascull@google.com, akpm@linux-foundation.org,
dvyukov@google.com, elver@google.com, tglx@linutronix.de,
arnd@arndb.de
Subject: Re: [PATCH 06/14] Fix CFLAGS for UBSAN_BOUNDS on Clang
Date: Tue, 15 Sep 2020 10:24:58 +0000 [thread overview]
Message-ID: <20200915102458.GA1650630@google.com> (raw)
In-Reply-To: <202009141509.CDDC8C8@keescook>
On Mon, Sep 14, 2020 at 03:13:14PM -0700, Kees Cook wrote:
> On Mon, Sep 14, 2020 at 05:27:42PM +0000, George-Aurelian Popescu wrote:
> > From: George Popescu <georgepope@google.com>
> >
> > When the kernel is compiled with Clang, UBSAN_BOUNDS inserts a brk after
> > the handler call, preventing it from printing any information processed
> > inside the buffer.
> > For Clang -fsanitize=bounds expands to -fsanitize=array-bounds and
> > -fsanitize=local-bounds, and the latter adds a brk after the handler
> > call
>
> That sounds like a compiler bug?
Actually in clang 12 documentation is written that -fsanitize=bounds
expands to that. GCC doesn't have those two options, only the
-fsanitize=bounds which looks similar to -fsanitize=array-bounds from
clang. So I don't see it as a compiler bug, just a misuse of flags.
> > Signed-off-by: George Popescu <georgepope@google.com>
> > ---
> > scripts/Makefile.ubsan | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
> > index 27348029b2b8..3d15ac346c97 100644
> > --- a/scripts/Makefile.ubsan
> > +++ b/scripts/Makefile.ubsan
> > @@ -4,7 +4,14 @@ ifdef CONFIG_UBSAN_ALIGNMENT
> > endif
> >
> > ifdef CONFIG_UBSAN_BOUNDS
> > - CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
> > + # For Clang -fsanitize=bounds translates to -fsanitize=array-bounds and
> > + # -fsanitize=local-bounds; the latter adds a brk right after the
> > + # handler is called.
> > + ifdef CONFIG_CC_IS_CLANG
> > + CFLAGS_UBSAN += $(call cc-option, -fsanitize=array-bounds)
>
> This would mean losing the local-bounds coverage? Isn't that for locally
> defined arrays on the stack?
This would mean losing the local-bounds coverage. I tried to test it without
local-bounds and with a locally defined array on the stack and it works fine
(the handler is called and the error reported). For me it feels like
--array-bounds and --local-bounds are triggered for the same type of
undefined_behaviours but they are handling them different.
> > + else
> > + CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
> > + endif
> > endif
> >
> > ifdef CONFIG_UBSAN_MISC
> > --
> > 2.28.0.618.gf4bc123cb7-goog
> >
>
> --
Thanks,
George
next prev parent reply other threads:[~2020-09-15 10:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 17:27 [PATCH 00/14] UBSan Enablement for hyp/nVHE code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 01/14] KVM: arm64: Enable UBSan instrumentation in nVHE hyp code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 02/14] KVM: arm64: Define a macro for storing a value inside a per_cpu variable George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 03/14] KVM: arm64: Add support for creating and checking a logging buffer inside hyp/nVHE George-Aurelian Popescu
2020-10-01 10:07 ` Andrew Scull
2020-09-14 17:27 ` [PATCH 04/14] KVM: arm64: Add support for buffer usage George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 05/14] KVM: arm64: Define a buffer that can pass UBSan data from hyp/nVHE to kernel George-Aurelian Popescu
2020-09-15 13:25 ` George Popescu
2020-10-01 10:51 ` Andrew Scull
2020-09-14 17:27 ` [PATCH 06/14] Fix CFLAGS for UBSAN_BOUNDS on Clang George-Aurelian Popescu
2020-09-14 21:17 ` Nick Desaulniers
2020-09-14 22:13 ` Kees Cook
2020-09-15 10:24 ` George Popescu [this message]
2020-09-15 11:18 ` Marco Elver
2020-09-15 12:01 ` George Popescu
2020-09-15 17:32 ` Marco Elver
2020-09-16 7:40 ` George Popescu
2020-09-16 8:32 ` Marco Elver
[not found] ` <20200916121401.GA3362356@google.com>
2020-09-16 13:40 ` Marco Elver
2020-09-17 6:37 ` Marco Elver
2020-09-17 11:35 ` George Popescu
2020-09-17 22:21 ` Kees Cook
2020-09-17 22:17 ` Kees Cook
2020-09-14 17:27 ` [PATCH 07/14] KVM: arm64: Enable UBSAN_BOUNDS for the both the kernel and hyp/nVHE George-Aurelian Popescu
2020-10-01 10:57 ` Andrew Scull
2020-09-14 17:27 ` [PATCH 08/14] KVM: arm64: Enable UBsan check for unreachable code inside hyp/nVHE code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 09/14] KVM: arm64: Enable shift out of bounds undefined behaviour check for hyp/nVHE George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 10/14] KVM: arm64: __ubsan_handle_load_invalid_value hyp/nVHE implementation George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 11/14] KVM: arm64: Detect type mismatch undefined behaviour from hyp/nVHE code George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 12/14] KVM: arm64: Detect arithmetic overflow is inside hyp/nVHE George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 13/14] KVM: arm64: Enable the CONFIG_TEST UBSan for PKVM George-Aurelian Popescu
2020-09-14 17:27 ` [PATCH 14/14] DO NOT MERGE: Enable configs to test the patch series George-Aurelian Popescu
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