Messages in this thread Patch in this message | | | From | Andy Lutomirski <> | Subject | [PATCH resend 4.9] hw_random: Don't use a stack buffer in add_early_randomness() | Date | Mon, 17 Oct 2016 10:06:27 -0700 |
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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: d3cc7996473a ("hwrng: fetch randomness only after device init") Signed-off-by: Andy Lutomirski <luto@kernel.org> ---
This fixes a crash in 4.9-rc1.
resending because I typoed the git send-email command. I stealthily added Matt's Tested-by, too.
drivers/char/hw_random/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index 9203f2d130c0..340f96e44642 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -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) -- 2.7.4
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