From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934225AbeE2MiN (ORCPT ); Tue, 29 May 2018 08:38:13 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:52360 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933874AbeE2MiL (ORCPT ); Tue, 29 May 2018 08:38:11 -0400 From: Prarit Bhargava To: linux-kernel@vger.kernel.org Cc: Prarit Bhargava , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, "Theodore Ts'o" , Arnd Bergmann , Greg Kroah-Hartman , Rik van Riel , Andrew Morton , Philippe Ombredanne , Kees Cook , "Jason A. Donenfeld" , Kate Stewart Subject: [PATCH] x86, random: Fix get_random_bytes() warning in x86 start_kernel Date: Tue, 29 May 2018 08:38:00 -0400 Message-Id: <20180529123800.19627-1-prarit@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After 43838a23a05f ("random: fix crng_ready() test") early boot calls to get_random_bytes() will warn on each cpu on x86 because the crng is not initialized. For example, random: get_random_bytes called from start_kernel+0x8e/0x587 with crng_init=0 x86 only uses get_random_bytes() for better randomization of the stack canary value so the warning is of no consequence. Export crng_ready() for x86 and test if the crng is initialized before calling get_random_bytes(). Signed-off-by: Prarit Bhargava Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Cc: "Theodore Ts'o" Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Rik van Riel Cc: Andrew Morton Cc: Philippe Ombredanne Cc: Kees Cook Cc: Prarit Bhargava Cc: "Jason A. Donenfeld" Cc: Kate Stewart --- arch/x86/include/asm/stackprotector.h | 3 ++- drivers/char/random.c | 5 ++++- include/linux/random.h | 1 + 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index 371b3a4af000..4e2223aa34fc 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -72,7 +72,8 @@ static __always_inline void boot_init_stack_canary(void) * there it already has some randomness on most systems. Later * on during the bootup the random pool has true entropy too. */ - get_random_bytes(&canary, sizeof(canary)); + if (crng_ready()) + get_random_bytes(&canary, sizeof(canary)); tsc = rdtsc(); canary += tsc + (tsc << 32UL); canary &= CANARY_MASK; diff --git a/drivers/char/random.c b/drivers/char/random.c index cd888d4ee605..003091d104bf 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -428,7 +428,10 @@ struct crng_state primary_crng = { * its value (from 0->1->2). */ static int crng_init = 0; -#define crng_ready() (likely(crng_init > 1)) +int crng_ready(void) +{ + return likely(crng_init > 1); +} static int crng_init_cnt = 0; static unsigned long crng_global_init_time = 0; #define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE) diff --git a/include/linux/random.h b/include/linux/random.h index 2ddf13b4281e..45616513abd9 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -196,4 +196,5 @@ static inline u32 next_pseudo_random32(u32 seed) return seed * 1664525 + 1013904223; } +extern int crng_ready(void); #endif /* _LINUX_RANDOM_H */ -- 2.14.3