57 lines
2.0 KiB
Diff
57 lines
2.0 KiB
Diff
From patchwork Mon Oct 17 17:06:27 2016
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: [resend,
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4.9] hw_random: Don't use a stack buffer in add_early_randomness()
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From: Andrew Lutomirski <luto@kernel.org>
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X-Patchwork-Id: 9380037
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Message-Id: <4169224b6858d1cf149f1a73f8a03603fa19076d.1476638125.git.luto@kernel.org>
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To: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
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Matt Mackall <mpm@selenic.com>, Herbert Xu <herbert@gondor.apana.org.au>,
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Rusty Russell <rusty@rustcorp.com.au>
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Cc: Jens Axboe <axboe@fb.com>, Matt Mullins <mmullins@mmlx.us>,
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Andy Lutomirski <luto@kernel.org>
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Date: Mon, 17 Oct 2016 10:06:27 -0700
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hw_random carefully avoids using a stack buffer except in
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add_early_randomness(). This causes a crash in virtio_rng if
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CONFIG_VMAP_STACK=y.
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Reported-by: Matt Mullins <mmullins@mmlx.us>
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Tested-by: Matt Mullins <mmullins@mmlx.us>
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Fixes: d3cc7996473a ("hwrng: fetch randomness only after device init")
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Signed-off-by: Andy Lutomirski <luto@kernel.org>
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---
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This fixes a crash in 4.9-rc1.
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resending because I typoed the git send-email command. I stealthily added
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Matt's Tested-by, too.
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drivers/char/hw_random/core.c | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
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index 9203f2d130c0..340f96e44642 100644
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--- a/drivers/char/hw_random/core.c
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+++ b/drivers/char/hw_random/core.c
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@@ -84,14 +84,14 @@ static size_t rng_buffer_size(void)
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static void add_early_randomness(struct hwrng *rng)
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{
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- unsigned char bytes[16];
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int bytes_read;
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+ size_t size = min_t(size_t, 16, rng_buffer_size());
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mutex_lock(&reading_mutex);
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- bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
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+ bytes_read = rng_get_data(rng, rng_buffer, size, 1);
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mutex_unlock(&reading_mutex);
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if (bytes_read > 0)
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- add_device_randomness(bytes, bytes_read);
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+ add_device_randomness(rng_buffer, bytes_read);
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}
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static inline void cleanup_rng(struct kref *kref)
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