From: Petr Mladek <pmladek@suse.com>
To: glider@google.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Eric Dumazet <edumazet@google.com>,
Wolfram Sang <wsa@the-dreams.de>,
Vegard Nossum <vegard.nossum@oracle.com>,
Dmitry Vyukov <dvyukov@google.com>,
linux-mm@kvack.org, viro@zeniv.linux.org.uk,
aryabinin@virtuozzo.com, luto@kernel.org,
ard.biesheuvel@linaro.org, arnd@arndb.de, hch@lst.de,
dmitry.torokhov@gmail.com, ericvh@gmail.com,
harry.wentland@amd.com, herbert@gondor.apana.org.au,
mingo@elte.hu, axboe@kernel.dk, martin.petersen@oracle.com,
schwidefsky@de.ibm.com, mst@redhat.com, monstr@monstr.eu,
sergey.senozhatsky@gmail.com, rostedt@goodmis.org,
tiwai@suse.com, tytso@mit.edu, tglx@linutronix.de,
gor@linux.ibm.com, iii@linux.ibm.com, mark.rutland@arm.com,
willy@infradead.org, rdunlap@infradead.org,
andreyknvl@google.com, elver@google.com
Subject: Re: [PATCH RFC v2 18/25] kmsan: call KMSAN hooks where needed
Date: Thu, 31 Oct 2019 12:49:16 +0100 [thread overview]
Message-ID: <20191031114916.ikz3phubs4jqdmnf@pathway.suse.cz> (raw)
In-Reply-To: <20191030142237.249532-19-glider@google.com>
On Wed 2019-10-30 15:22:30, glider@google.com wrote:
> Insert KMSAN hooks that check for potential memory errors and/or make
> necessary bookkeeping changes:
> - allocate/split/deallocate metadata pages in
> alloc_pages()/split_page()/free_page();
> - clear page shadow and origins in clear_page(), copy_user_highpage();
> - copy page metadata in copy_highpage(), wp_page_copy();
> - handle vmap()/vunmap()/iounmap();
> - handle task creation and deletion;
> - initialize result of vscnprintf() in vprintk_store();
> - call softirq entry/exit hooks in kernel/softirq.c;
> - check/initialize memory sent to/read from USB, I2C, and network
>
> Signed-off-by: Alexander Potapenko <glider@google.com>
> To: Alexander Potapenko <glider@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Vegard Nossum <vegard.nossum@oracle.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: linux-mm@kvack.org
> ---
>
> v2:
> - dropped call to kmsan_handle_vprintk, updated comment in printk.c
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index ca65327a6de8..4b0dbed0333a 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1914,7 +1914,13 @@ int vprintk_store(int facility, int level,
> * The printf needs to come first; we need the syslog
> * prefix which might be passed-in as a parameter.
> */
> - text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
> + /*
Please, separate the two comments with an empty line instead of using
*/ and /*.
> + * If any of vscnprintf() arguments is uninitialized, KMSAN will report
> + * one or more errors and also probably mark text_len as uninitialized.
> + * Initialize |text_len| to prevent the errors from spreading further.
> + */
> + text_len = KMSAN_INIT_VALUE(vscnprintf(text, sizeof(textbuf), fmt,
> + args));
Please, keep it on a single line. This seems to be the case where
the 80-characters limit rule just breaks readability.
I still think that KMSAN should report only the first use of
an uninitialized value. It should _not_ report locations where
the value is spread. The root of the problem must be fixed.
Everything else looks like an unnecessary noise.
Well, this fake initialization is added only 4 times in this patchset.
So, it is not a disaster. I could live with the change. And if
people like/want this behavior...
With the two cosmetic changes, feel free to use:
Acked-by: Petr Mladek <pmladek@suse.com> # printk part
Best Regards,
Petr
next prev parent reply other threads:[~2019-10-31 11:49 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 14:22 [PATCH RFC v2 00/25] Add KernelMemorySanitizer infrastructure glider
2019-10-30 14:22 ` [PATCH RFC v2 01/25] stackdepot: check depot_index before accessing the stack slab glider
2019-10-30 14:22 ` [PATCH RFC v2 02/25] stackdepot: prevent Clang from optimizing away stackdepot_memcmp() glider
2019-11-01 5:50 ` Sergey Senozhatsky
2019-11-06 11:43 ` Alexander Potapenko
2019-11-07 6:08 ` Sergey Senozhatsky
2019-11-07 9:04 ` Arnd Bergmann
2019-11-07 9:22 ` Alexander Potapenko
2019-11-07 9:28 ` Arnd Bergmann
2019-11-07 9:43 ` Alexander Potapenko
[not found] ` <47fdac13-fa2c-2acd-2480-5e6d4db208f8@virtuozzo.com>
2019-11-07 10:00 ` Arnd Bergmann
[not found] ` <6875c6e6-2f1f-f8e6-e5d7-d451c48397ff@virtuozzo.com>
2019-11-07 10:30 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 03/25] kasan: stackdepot: move filter_irq_stacks() to stackdepot.c glider
2019-10-30 14:22 ` [PATCH RFC v2 04/25] stackdepot: reserve 5 extra bits in depot_stack_handle_t glider
2019-10-30 14:22 ` [PATCH RFC v2 05/25] kmsan: add ReST documentation glider
2019-10-30 14:22 ` [PATCH RFC v2 06/25] kmsan: gfp: introduce __GFP_NO_KMSAN_SHADOW glider
2019-10-30 14:22 ` [PATCH RFC v2 07/25] kmsan: introduce __no_sanitize_memory and __SANITIZE_MEMORY__ glider
2019-10-30 15:50 ` Andrey Konovalov
2019-11-01 12:52 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 08/25] kmsan: reduce vmalloc space glider
2019-10-30 14:22 ` [PATCH RFC v2 09/25] kmsan: add KMSAN runtime glider
2019-11-08 12:08 ` Dmitry Vyukov
2019-11-08 12:17 ` Dmitry Vyukov
2019-11-21 12:06 ` Alexander Potapenko
2019-11-13 8:13 ` Wolfram Sang
2019-11-21 12:01 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 10/25] kmsan: define READ_ONCE_NOCHECK() glider
2019-11-05 14:21 ` Mark Rutland
2019-11-21 12:08 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 11/25] kmsan: x86: sync metadata pages on page fault glider
2019-10-30 14:22 ` [PATCH RFC v2 12/25] kmsan: add tests for KMSAN glider
2019-10-30 14:22 ` [PATCH RFC v2 13/25] kmsan: make READ_ONCE_TASK_STACK() return initialized values glider
2019-10-30 14:22 ` [PATCH RFC v2 14/25] kmsan: Kconfig changes to disable options incompatible with KMSAN glider
2019-10-30 14:34 ` Qian Cai
2019-10-30 14:34 ` Christoph Hellwig
2019-10-30 14:22 ` [PATCH RFC v2 15/25] kmsan: Changing existing files to enable KMSAN builds glider
2019-10-30 14:36 ` Christoph Hellwig
2019-10-30 14:22 ` [PATCH RFC v2 16/25] kmsan: disable KMSAN instrumentation for certain kernel parts glider
2019-10-30 14:22 ` [PATCH RFC v2 17/25] kmsan: mm: call KMSAN hooks from SLUB code glider
2019-10-30 16:07 ` Andrey Konovalov
2019-10-30 14:22 ` [PATCH RFC v2 18/25] kmsan: call KMSAN hooks where needed glider
2019-10-31 11:49 ` Petr Mladek [this message]
2019-11-01 8:26 ` Sergey Senozhatsky
2019-11-05 14:12 ` Alexander Potapenko
2019-11-06 9:04 ` Petr Mladek
2019-11-06 9:07 ` Sergey Senozhatsky
2019-10-30 14:22 ` [PATCH RFC v2 19/25] kmsan: disable instrumentation of certain functions glider
2019-10-30 14:22 ` [PATCH RFC v2 20/25] kmsan: unpoison |tlb| in arch_tlb_gather_mmu() glider
2019-10-30 14:22 ` [PATCH RFC v2 21/25] kmsan: use __msan_memcpy() where possible glider
2019-10-30 14:22 ` [PATCH RFC v2 22/25] kmsan: unpoisoning buffers from devices etc glider
2019-10-30 14:38 ` Christoph Hellwig
2019-11-05 15:02 ` Alexander Potapenko
2019-11-07 13:00 ` Alexander Potapenko
2019-11-13 11:07 ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 23/25] kmsan: hooks for copy_to_user() and friends glider
2019-10-30 14:22 ` [PATCH RFC v2 24/25] kmsan: disable strscpy() optimization under KMSAN glider
2019-10-30 14:22 ` [PATCH RFC v2 25/25] net: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN glider
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