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Commit ee7998c5 authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
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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: default avatarKees Cook <keescook@chromium.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Lokesh Vutla <lokeshvutla@ti.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9380fa60

drivers/char/random.c

+5 −0
Original line number Diff line number Diff line
@@ -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);

init/main.c

+1 −0
Original line number Diff line number Diff line
@@ -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();