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From: glider@google.com
To: Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>,  "Theodore Ts'o" <tytso@mit.edu>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	 "Martin K. Petersen" <martin.petersen@oracle.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	 Christoph Hellwig <hch@lst.de>,
	Eric Dumazet <edumazet@google.com>,
	Eric Van Hensbergen <ericvh@gmail.com>,
	 Takashi Iwai <tiwai@suse.com>,
	Vegard Nossum <vegard.nossum@oracle.com>,
	 Dmitry Vyukov <dvyukov@google.com>,
	Matthew Wilcox <willy@infradead.org>,
	linux-mm@kvack.org
Cc: glider@google.com, viro@zeniv.linux.org.uk,
	adilger.kernel@dilger.ca,  andreyknvl@google.com,
	aryabinin@virtuozzo.com, luto@kernel.org,
	 ard.biesheuvel@linaro.org, arnd@arndb.de, hch@infradead.org,
	 darrick.wong@oracle.com, davem@davemloft.net,
	ebiggers@google.com,  gregkh@linuxfoundation.org,
	harry.wentland@amd.com,  herbert@gondor.apana.org.au,
	iii@linux.ibm.com, mingo@elte.hu,  jasowang@redhat.com,
	m.szyprowski@samsung.com, elver@google.com,
	 mark.rutland@arm.com, schwidefsky@de.ibm.com, monstr@monstr.eu,
	 pmladek@suse.com, cai@lca.pw, rdunlap@infradead.org,
	robin.murphy@arm.com,  sergey.senozhatsky@gmail.com,
	rostedt@goodmis.org, tglx@linutronix.de,  gor@linux.ibm.com,
	wsa@the-dreams.de
Subject: [PATCH RFC v3 29/36] kmsan: handle /dev/[u]random
Date: Fri, 22 Nov 2019 12:26:14 +0100
Message-ID: <20191122112621.204798-30-glider@google.com> (raw)
In-Reply-To: <20191122112621.204798-1-glider@google.com>

The random number generator may use uninitialized memory, but it may not
return uninitialized values. Unpoison the output buffer in
_extract_crng() to prevent false reports.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org

---
This patch was previously known as "kmsan: unpoisoning buffers from
devices etc.", but it turned out to be possible to drop most of the
annotations from that patch, so it only relates to /dev/random now.

Change-Id: Id460e7a86ce564f1357469f53d0c7410ca08f0e9
---
 drivers/char/random.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index de434feb873a..9b1639c73b65 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -320,6 +320,7 @@
 #include <linux/fs.h>
 #include <linux/genhd.h>
 #include <linux/interrupt.h>
+#include <linux/kmsan-checks.h>
 #include <linux/mm.h>
 #include <linux/nodemask.h>
 #include <linux/spinlock.h>
@@ -1061,6 +1062,11 @@ static void _extract_crng(struct crng_state *crng,
 	spin_lock_irqsave(&crng->lock, flags);
 	if (arch_get_random_long(&v))
 		crng->state[14] ^= v;
+	/*
+	 * Regardless of where the random data comes from, KMSAN should treat
+	 * it as initialized.
+	 */
+	kmsan_unpoison_shadow(crng->state, sizeof(crng->state));
 	chacha20_block(&crng->state[0], out);
 	if (crng->state[12] == 0)
 		crng->state[13]++;
-- 
2.24.0.432.g9d3f5f5b63-goog



  parent reply index

Thread overview: 120+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-22 11:25 [PATCH RFC v3 00/36] Add KernelMemorySanitizer infrastructure glider
2019-11-22 11:25 ` [PATCH RFC v3 01/36] stackdepot: check depot_index before accessing the stack slab glider
2019-11-27 14:22   ` Marco Elver
2019-11-22 11:25 ` [PATCH RFC v3 02/36] stackdepot: build with -fno-builtin glider
2019-11-27 14:22   ` Marco Elver
2019-11-22 11:25 ` [PATCH RFC v3 03/36] kasan: stackdepot: move filter_irq_stacks() to stackdepot.c glider
2019-11-27 14:22   ` Marco Elver
2019-11-27 14:56     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 04/36] stackdepot: reserve 5 extra bits in depot_stack_handle_t glider
2019-11-27 14:23   ` Marco Elver
2019-11-22 11:25 ` [PATCH RFC v3 05/36] kmsan: add ReST documentation glider
2019-11-27 14:22   ` Marco Elver
2019-12-03 12:42     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 06/36] kmsan: gfp: introduce __GFP_NO_KMSAN_SHADOW glider
2019-11-27 14:48   ` Marco Elver
2019-12-03 12:57     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 07/36] kmsan: introduce __no_sanitize_memory and __SANITIZE_MEMORY__ glider
2019-11-28 13:13   ` Marco Elver
2019-11-29 16:09   ` Andrey Konovalov
2019-12-16 11:35     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 08/36] kmsan: reduce vmalloc space glider
2019-11-28 13:30   ` Marco Elver
2019-11-22 11:25 ` [PATCH RFC v3 09/36] kmsan: add KMSAN bits to struct page and struct task_struct glider
2019-11-28 13:44   ` Marco Elver
2019-11-28 14:05     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 10/36] kmsan: add KMSAN runtime glider
2019-11-24 19:44   ` Wolfram Sang
2019-11-25  9:14     ` Alexander Potapenko
2019-11-29 16:07   ` Marco Elver
2019-12-19 14:16     ` Alexander Potapenko
2019-12-02 15:39   ` Andrey Konovalov
2019-12-20 18:58     ` Alexander Potapenko
2019-12-03 14:34   ` Andrey Konovalov
2019-11-22 11:25 ` [PATCH RFC v3 11/36] kmsan: stackdepot: don't allocate KMSAN metadata for stackdepot glider
2019-11-29 14:52   ` Andrey Konovalov
2019-12-03 14:27     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 12/36] kmsan: define READ_ONCE_NOCHECK() glider
2019-12-02 10:03   ` Marco Elver
2019-12-03 12:45     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 13/36] kmsan: make READ_ONCE_TASK_STACK() return initialized values glider
2019-12-02 10:07   ` Marco Elver
2019-12-05 15:52     ` Alexander Potapenko
2019-11-22 11:25 ` [PATCH RFC v3 14/36] kmsan: x86: sync metadata pages on page fault glider
2019-11-22 11:26 ` [PATCH RFC v3 15/36] kmsan: add tests for KMSAN glider
2019-11-29 14:14   ` Andrey Konovalov
2019-12-05 14:30     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 16/36] crypto: kmsan: disable accelerated configs under KMSAN glider
2019-12-02 13:25   ` Marco Elver
2019-12-05 14:51     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 17/36] kmsan: x86: disable UNWINDER_ORC " glider
2019-12-02 13:30   ` Marco Elver
2019-11-22 11:26 ` [PATCH RFC v3 18/36] kmsan: disable LOCK_DEBUGGING_SUPPORT glider
2019-12-02 13:33   ` Marco Elver
2019-12-03 14:34     ` Alexander Potapenko
2019-12-03 15:00       ` Qian Cai
2019-12-03 15:14         ` Alexander Potapenko
2019-12-03 18:02           ` Qian Cai
2019-12-03 18:38           ` Steven Rostedt
2019-12-04  8:41             ` Alexander Potapenko
2019-12-04 12:22               ` Petr Mladek
2019-12-04 13:12                 ` Qian Cai
2019-12-04 16:24                   ` Alexander Potapenko
2019-12-04 18:03                     ` Qian Cai
2019-11-22 11:26 ` [PATCH RFC v3 20/36] kmsan: x86: increase stack sizes in KMSAN builds glider
2019-12-02 14:31   ` Marco Elver
2019-11-22 11:26 ` [PATCH RFC v3 21/36] kmsan: disable KMSAN instrumentation for certain kernel parts glider
2019-11-29 15:07   ` Andrey Konovalov
2019-12-10 10:35     ` Alexander Potapenko
2019-12-10 12:38       ` Alexander Potapenko
2019-12-10 12:43       ` Qian Cai
2019-11-22 11:26 ` [PATCH RFC v3 22/36] kmsan: mm: call KMSAN hooks from SLUB code glider
2019-12-02 15:36   ` Marco Elver
2019-12-10 12:07     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 23/36] kmsan: call KMSAN hooks where needed glider
2019-11-26 10:17   ` Petr Mladek
2019-11-26 10:52     ` Alexander Potapenko
2019-11-29 16:21   ` Andrey Konovalov
2019-12-16 11:30     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 24/36] kmsan: disable instrumentation of certain functions glider
2019-11-29 14:59   ` Andrey Konovalov
2019-12-18 10:02     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 25/36] kmsan: unpoison |tlb| in arch_tlb_gather_mmu() glider
2019-11-29 15:08   ` Andrey Konovalov
2019-12-03 14:19     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 26/36] kmsan: use __msan_memcpy() where possible glider
2019-11-29 15:13   ` Andrey Konovalov
2019-12-05 15:46     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 27/36] kmsan: hooks for copy_to_user() and friends glider
2019-11-29 15:34   ` Andrey Konovalov
2019-12-05 16:00     ` Alexander Potapenko
2019-12-05 16:44       ` Andrey Konovalov
2019-12-11 14:22         ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 28/36] kmsan: enable KMSAN builds glider
2019-11-29 15:55   ` Andrey Konovalov
2019-12-11 12:51     ` Alexander Potapenko
2019-11-22 11:26 ` glider [this message]
2019-11-22 11:26 ` [PATCH RFC v3 30/36] kmsan: virtio: check/unpoison scatterlist in vring_map_one_sg() glider
2019-11-22 11:26 ` [PATCH RFC v3 31/36] kmsan: disable strscpy() optimization under KMSAN glider
2019-12-02 15:51   ` Marco Elver
2019-12-02 16:23     ` Alexander Potapenko
2019-12-03 11:19       ` Alexander Potapenko
2019-12-03 11:24         ` Marco Elver
2019-12-03 11:27           ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 32/36] kmsan: add iomap support glider
2019-12-03 12:50   ` Marco Elver
2019-12-03 14:07     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 33/36] kmsan: dma: unpoison memory mapped by dma_direct_map_page() glider
2019-11-22 11:26 ` [PATCH RFC v3 34/36] kmsan: disable physical page merging in biovec glider
2019-12-03 12:54   ` Marco Elver
2019-12-03 13:38     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 35/36] kmsan: ext4: skip block merging logic in ext4_mpage_readpages for KMSAN glider
2019-11-25 16:05   ` Robin Murphy
2019-11-25 17:03     ` Alexander Potapenko
2019-12-03 14:22   ` Marco Elver
2019-12-05 14:31     ` Alexander Potapenko
2019-11-22 11:26 ` [PATCH RFC v3 36/36] net: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN glider
2019-12-03 14:17   ` Marco Elver
2019-12-05 14:37     ` Alexander Potapenko
2019-11-29 14:39 ` [PATCH RFC v3 00/36] Add KernelMemorySanitizer infrastructure Marco Elver
2019-12-02 16:02   ` Alexander Potapenko

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