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authorKees Cook <keescook@chromium.org>2017-07-12 14:34:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-12 16:26:00 -0700
commitee7998c50c2697737c6530431709f77c852bf0d6 (patch)
treead6f1c9946eae9286b3e5495cef00e3791256920 /drivers/char
parent9380fa60b10ebd6ee7c3fcdb2cf162f4d7cf9fc5 (diff)
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 <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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/random.c5
1 files changed, 5 insertions, 0 deletions
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);