From: Kees Cook <keescook@chromium.org>
To: Siddhesh Poyarekar <siddhesh@gotplt.org>
Cc: linux-hardening@vger.kernel.org, Miguel Ojeda <ojeda@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Nick Desaulniers <ndesaulniers@google.com>,
Nathan Chancellor <nathan@kernel.org>, Tom Rix <trix@redhat.com>,
llvm@lists.linux.dev, Juergen Gross <jgross@suse.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] fortify: Use __builtin_dynamic_object_size() when available
Date: Tue, 22 Nov 2022 21:15:51 -0800 [thread overview]
Message-ID: <202211222113.10003CF8FD@keescook> (raw)
In-Reply-To: <0da67f73-dd73-7e6d-74c2-14aec5d79902@gotplt.org>
On Tue, Nov 22, 2022 at 05:20:37AM -0500, Siddhesh Poyarekar wrote:
> On 2022-09-20 15:22, Kees Cook wrote:
> > Since the commits starting with c37495d6254c ("slab: add __alloc_size
> > attributes for better bounds checking"), the compilers have runtime
> > allocation size hints available in some places. This was immediately
> > available to CONFIG_UBSAN_BOUNDS, but CONFIG_FORTIFY_SOURCE needed
> > updating to explicitly make use the hints via the associated
> > __builtin_dynamic_object_size() helper. Detect and use the builtin when
> > it is available, increasing the accuracy of the mitigation. When runtime
> > sizes are not available, __builtin_dynamic_object_size() falls back to
> > __builtin_object_size(), leaving the existing bounds checking unchanged.
> >
> > Additionally update the VMALLOC_LINEAR_OVERFLOW LKDTM test to make the
> > hint invisible, otherwise the architectural defense is not exercised
> > (the buffer overflow is detected in the memset() rather than when it
> > crosses the edge of the allocation).
> >
> > Cc: Miguel Ojeda <ojeda@kernel.org>
> > Cc: Siddhesh Poyarekar <siddhesh@gotplt.org>
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Nick Desaulniers <ndesaulniers@google.com>
> > Cc: Nathan Chancellor <nathan@kernel.org>
> > Cc: Tom Rix <trix@redhat.com>
> > Cc: linux-hardening@vger.kernel.org
> > Cc: llvm@lists.linux.dev
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> > drivers/misc/lkdtm/heap.c | 1 +
> > include/linux/compiler_attributes.h | 5 +++++
> > include/linux/fortify-string.h | 7 +++++++
> > 3 files changed, 13 insertions(+)
>
> Hi Kees,
>
> Circling back on this, I noticed that all but this patch got pulled into
> Linus' tree. Is there a reason why this has been held back?
Hi!
Yeah, it depended on a bunch of various clean-ups, which have finally
managed to land. It's late enough in the devel cycle that I suspect I
will hold this one back until after the merge window and then make sure
it has plenty of time to bake in -next. If the rest of the patches
continue to behave, I may change my mind... :)
-Kees
--
Kees Cook
next prev parent reply other threads:[~2022-11-23 5:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 19:21 [PATCH 0/4] fortify: Use __builtin_dynamic_object_size() when available Kees Cook
2022-09-20 19:21 ` [PATCH 1/4] x86/entry: Work around Clang __bdos() bug Kees Cook
2022-09-21 0:07 ` Boris Ostrovsky
2022-09-20 19:22 ` [PATCH 2/4] fortify: Explicitly check bounds are compile-time constants Kees Cook
2022-09-21 11:48 ` Siddhesh Poyarekar
2022-09-22 3:46 ` Kees Cook
2022-09-20 19:22 ` [PATCH 3/4] fortify: Convert to struct vs member helpers Kees Cook
2022-09-20 19:22 ` [PATCH 4/4] fortify: Use __builtin_dynamic_object_size() when available Kees Cook
2022-09-21 11:24 ` Miguel Ojeda
2022-09-21 11:43 ` Siddhesh Poyarekar
2022-09-22 3:33 ` Kees Cook
2022-09-22 14:45 ` Siddhesh Poyarekar
2022-11-22 10:20 ` Siddhesh Poyarekar
2022-11-23 5:15 ` Kees Cook [this message]
2022-11-23 15:29 ` Siddhesh Poyarekar
2023-01-13 15:59 ` linux-next - bxnt buffer overflow in strnlen Niklas Cassel
2023-01-13 16:08 ` linux-next - bnxt " Niklas Cassel
2023-01-13 22:44 ` Kees Cook
2023-01-16 10:56 ` Niklas Cassel
2022-09-22 20:26 ` [PATCH 0/4] fortify: Use __builtin_dynamic_object_size() when available Siddhesh Poyarekar
2022-09-23 0:20 ` Kees Cook
2022-09-23 0:55 ` Siddhesh Poyarekar
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