From 08475dab7cf5b610ea2420828e97c54f5f370d7d Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 26 Sep 2022 18:32:25 +0200
Subject: [PATCH] kfence: use better stack hash seed
As of the prior commit, the RNG will have incorporated both a cycle
counter value and RDRAND, in addition to various other environmental
noise. Therefore, using get_random_u32() will supply a stronger seed
than simply using random_get_entropy(). N.B.: random_get_entropy()
should be considered an internal API of random.c and not generally
consumed.
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
mm/kfence/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index c252081b11dfe..239b1b4b094fa 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -864,7 +864,7 @@ static void kfence_init_enable(void)
void __init kfence_init(void)
{
- stack_hash_seed = (u32)random_get_entropy();
+ stack_hash_seed = get_random_u32();
/* Setting kfence_sample_interval to 0 on boot disables KFENCE. */
if (!kfence_sample_interval)
--
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