From ee7998c50c2697737c6530431709f77c852bf0d6 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 12 Jul 2017 14:34:04 -0700 Subject: [PATCH] random: do not ignore early device randomness The add_device_randomness() function would ignore incoming bytes if the crng wasn't ready. This additionally makes sure to make an early enough call to add_latent_entropy() to influence the initial stack canary, which is especially important on non-x86 systems where it stays the same through the life of the boot. Link: http://lkml.kernel.org/r/20170626233038.GA48751@beast Signed-off-by: Kees Cook Cc: "Theodore Ts'o" Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Jessica Yu Cc: Steven Rostedt (VMware) Cc: Viresh Kumar Cc: Tejun Heo Cc: Prarit Bhargava Cc: Lokesh Vutla Cc: Nicholas Piggin Cc: AKASHI Takahiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/random.c | 5 +++++ init/main.c | 1 + 2 files changed, 6 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 01a260f67437..23cab7a8c1c1 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -987,6 +987,11 @@ void add_device_randomness(const void *buf, unsigned int size) unsigned long time = random_get_entropy() ^ jiffies; unsigned long flags; + if (!crng_ready()) { + crng_fast_load(buf, size); + return; + } + trace_add_device_randomness(size, _RET_IP_); spin_lock_irqsave(&input_pool.lock, flags); _mix_pool_bytes(&input_pool, buf, size); diff --git a/init/main.c b/init/main.c index df58a416dd1d..052481fbe363 100644 --- a/init/main.c +++ b/init/main.c @@ -518,6 +518,7 @@ asmlinkage __visible void __init start_kernel(void) /* * Set up the initial canary ASAP: */ + add_latent_entropy(); boot_init_stack_canary(); cgroup_init_early(); -- 2.20.1