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hwrng: core - Don't use a stack buffer in add_early_randomness()

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hw_random carefully avoids using a stack buffer except in
add_early_randomness().  This causes a crash in virtio_rng if
CONFIG_VMAP_STACK=y.

Reported-by: Matt Mullins <mmullins@mmlx.us>
Tested-by: Matt Mullins <mmullins@mmlx.us>
Fixes: d3cc799647 ("hwrng: fetch randomness only after device init")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Andrew Lutomirski 2016-10-17 10:06:27 -07:00 committed by Herbert Xu
parent 1001354ca3
commit 6d4952d9d9
1 changed files with 3 additions and 3 deletions
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6
drivers/char/hw_random/core.c
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@ -84,14 +84,14 @@ static size_t rng_buffer_size(void)
static void add_early_randomness(struct hwrng *rng)
{
unsigned char bytes[16];
int bytes_read;
size_t size = min_t(size_t, 16, rng_buffer_size());
mutex_lock(&reading_mutex);
bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
bytes_read = rng_get_data(rng, rng_buffer, size, 1);
mutex_unlock(&reading_mutex);
if (bytes_read > 0)
add_device_randomness(bytes, bytes_read);
add_device_randomness(rng_buffer, bytes_read);
}
static inline void cleanup_rng(struct kref *kref)