lkml.org 
[lkml]   [2016]   [Nov]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.8 71/92] hwrng: core - Dont use a stack buffer in add_early_randomness()
Date
4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Lutomirski <luto@kernel.org>

commit 6d4952d9d9d4dc2bb9c0255d95a09405a1e958f7 upstream.

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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/char/hw_random/core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- 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)

\
 
 \ /
  Last update: 2016-11-17 11:38    [W:0.337 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site