This is a note to let you know that I've just added the patch titled hwrng: core - Don't use a stack buffer in add_early_randomness() to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: hwrng-core-don-t-use-a-stack-buffer-in-add_early_randomness.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 6d4952d9d9d4dc2bb9c0255d95a09405a1e958f7 Mon Sep 17 00:00:00 2001 From: Andrew Lutomirski <luto@xxxxxxxxxx> Date: Mon, 17 Oct 2016 10:06:27 -0700 Subject: hwrng: core - Don't use a stack buffer in add_early_randomness() From: Andrew Lutomirski <luto@xxxxxxxxxx> 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@xxxxxxx> Tested-by: Matt Mullins <mmullins@xxxxxxx> Fixes: d3cc7996473a ("hwrng: fetch randomness only after device init") Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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) Patches currently in stable-queue which might be from luto@xxxxxxxxxx are queue-4.4/hwrng-core-don-t-use-a-stack-buffer-in-add_early_randomness.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html