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Fri, 22 Nov 2019 03:27:56 -0800 (PST) Date: Fri, 22 Nov 2019 12:26:14 +0100 In-Reply-To: <20191122112621.204798-1-glider@google.com> Message-Id: <20191122112621.204798-30-glider@google.com> Mime-Version: 1.0 References: <20191122112621.204798-1-glider@google.com> X-Mailer: git-send-email 2.24.0.432.g9d3f5f5b63-goog Subject: [PATCH RFC v3 29/36] kmsan: handle /dev/[u]random From: glider@google.com To: Andrew Morton , Jens Axboe , "Theodore Ts'o" , Dmitry Torokhov , "Martin K. Petersen" , "Michael S. Tsirkin" , Christoph Hellwig , Eric Dumazet , Eric Van Hensbergen , Takashi Iwai , Vegard Nossum , Dmitry Vyukov , Matthew Wilcox , 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 To: Alexander Potapenko Cc: Andrew Morton Cc: Jens Axboe Cc: "Theodore Ts'o" Cc: Dmitry Torokhov Cc: Martin K. Petersen Cc: "Michael S. Tsirkin" Cc: Christoph Hellwig Cc: Eric Dumazet Cc: Eric Van Hensbergen Cc: Takashi Iwai Cc: Vegard Nossum Cc: Dmitry Vyukov Cc: Matthew Wilcox 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 #include #include +#include #include #include #include @@ -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]++;