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From: Alexander Potapenko <glider@google.com>
To: glider@google.com
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>, Christoph Hellwig <hch@lst.de>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Ilya Leoshkevich <iii@linux.ibm.com>,
	Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Kees Cook <keescook@chromium.org>, Marco Elver <elver@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Matthew Wilcox <willy@infradead.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Pekka Enberg <penberg@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Petr Mladek <pmladek@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Vegard Nossum <vegard.nossum@oracle.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Andrey Konovalov <andreyknvl@gmail.com>
Subject: [PATCH v2 46/48] x86: fs: kmsan: disable CONFIG_DCACHE_WORD_ACCESS
Date: Tue, 29 Mar 2022 14:40:15 +0200	[thread overview]
Message-ID: <20220329124017.737571-47-glider@google.com> (raw)
In-Reply-To: <20220329124017.737571-1-glider@google.com>

dentry_string_cmp() calls read_word_at_a_time(), which might read
uninitialized bytes to optimize string comparisons.
Disabling CONFIG_DCACHE_WORD_ACCESS should prohibit this optimization,
as well as (probably) similar ones.

Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
---
Link: https://linux-review.googlesource.com/id/I4c0073224ac2897cafb8c037362c49dda9cfa133
---
 arch/x86/Kconfig | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 86df15017f79d..646a7849be4cf 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -126,7 +126,9 @@ config X86
 	select CLKEVT_I8253
 	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
 	select CLOCKSOURCE_WATCHDOG
-	select DCACHE_WORD_ACCESS
+	# Word-size accesses may read uninitialized data past the trailing \0
+	# in strings and cause false KMSAN reports.
+	select DCACHE_WORD_ACCESS		if !KMSAN
 	select DYNAMIC_SIGFRAME
 	select EDAC_ATOMIC_SCRUB
 	select EDAC_SUPPORT
-- 
2.35.1.1021.g381101b075-goog


  parent reply	other threads:[~2022-03-29 12:55 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-29 12:39 [PATCH v2 00/48] Add KernelMemorySanitizer infrastructure Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 01/48] x86: add missing include to sparsemem.h Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 02/48] stackdepot: reserve 5 extra bits in depot_stack_handle_t Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 03/48] kasan: common: adapt to the new prototype of __stack_depot_save() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 04/48] instrumented.h: allow instrumenting both sides of copy_from_user() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 05/48] x86: asm: instrument usercopy in get_user() and __put_user_size() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 06/48] asm-generic: instrument usercopy in cacheflush.h Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 07/48] kmsan: add ReST documentation Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 08/48] kmsan: introduce __no_sanitize_memory and __no_kmsan_checks Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 09/48] kmsan: mark noinstr as __no_sanitize_memory Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 10/48] x86: kmsan: pgtable: reduce vmalloc space Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 11/48] libnvdimm/pfn_dev: increase MAX_STRUCT_PAGE_SIZE Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 12/48] kcsan: clang: retire CONFIG_KCSAN_KCOV_BROKEN Alexander Potapenko
2022-03-30  6:00   ` Marco Elver
2022-03-29 12:39 ` [PATCH v2 13/48] kmsan: add KMSAN runtime core Alexander Potapenko
2022-03-30  8:58   ` Peter Zijlstra
2022-03-30  9:41     ` Peter Zijlstra
2022-04-04 14:39   ` Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 14/48] kmsan: implement kmsan_init(), initialize READ_ONCE_NOCHECK() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 15/48] kmsan: disable instrumentation of unsupported common kernel code Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 16/48] MAINTAINERS: add entry for KMSAN Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 17/48] kmsan: mm: maintain KMSAN metadata for page operations Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 18/48] kmsan: mm: call KMSAN hooks from SLUB code Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 19/48] kmsan: handle task creation and exiting Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 20/48] kmsan: init: call KMSAN initialization routines Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 21/48] instrumented.h: add KMSAN support Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 22/48] kmsan: unpoison @tlb in arch_tlb_gather_mmu() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 23/48] kmsan: add iomap support Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 24/48] Input: libps2: mark data received in __ps2_command() as initialized Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 25/48] kmsan: dma: unpoison DMA mappings Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 26/48] kmsan: virtio: check/unpoison scatterlist in vring_map_one_sg() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 27/48] kmsan: handle memory sent to/from USB Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 28/48] kmsan: instrumentation.h: add instrumentation_begin_with_regs() Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 29/48] kmsan: entry: handle register passing from uninstrumented code Alexander Potapenko
2022-03-29 12:39 ` [PATCH v2 30/48] kmsan: add tests for KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 31/48] kernel: kmsan: don't instrument stacktrace.c Alexander Potapenko
2022-04-04 14:56   ` Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 32/48] kmsan: disable strscpy() optimization under KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 33/48] crypto: kmsan: disable accelerated configs " Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 34/48] kmsan: disable physical page merging in biovec Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 35/48] kmsan: block: skip bio block merging logic for KMSAN Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 36/48] kmsan: kcov: unpoison area->list in kcov_remote_area_put() Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 37/48] security: kmsan: fix interoperability with auto-initialization Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 38/48] objtool: kmsan: list KMSAN API functions as uaccess-safe Alexander Potapenko
2022-03-30  8:46   ` Peter Zijlstra
2022-04-14 15:30     ` Alexander Potapenko
2022-04-14 15:38       ` Peter Zijlstra
2022-03-29 12:40 ` [PATCH v2 39/48] x86: kmsan: make READ_ONCE_TASK_STACK() return initialized values Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 40/48] x86: kmsan: disable instrumentation of unsupported code Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 41/48] x86: kmsan: skip shadow checks in __switch_to() Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 42/48] x86: kmsan: handle open-coded assembly in lib/iomem.c Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 43/48] x86: kmsan: use __msan_ string functions where possible Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 44/48] x86: kmsan: sync metadata pages on page fault Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 45/48] x86: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN Alexander Potapenko
2022-03-29 12:40 ` Alexander Potapenko [this message]
2022-03-29 12:40 ` [PATCH v2 47/48] x86: kmsan: handle register passing from uninstrumented code Alexander Potapenko
2022-03-29 12:40 ` [PATCH v2 48/48] x86: kmsan: enable KMSAN builds for x86 Alexander Potapenko

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