From: David Laight <david.laight.linux@gmail.com>
To: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>
Cc: David Laight <david.laight.linux@gmail.com>,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
Kir Chou <note351@hotmail.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Mark Rutland <mark.rutland@arm.com>, Kees Cook <kees@kernel.org>
Subject: [PATCH next 7/7] random32: Simplify prandom_seed_full_state()
Date: Mon, 2 Nov 2026 20:05:22 +0000 [thread overview]
Message-ID: <20261102200522.3337-8-david.laight.linux@gmail.com> (raw)
In-Reply-To: <20261102200522.3337-1-david.laight.linux@gmail.com>
Instead of offsetting values that would be treated as zero, just set
a bit that ensures they wont be treated as zero.
Reduces the number of initial states from just under 2**113 to 2**109.
This really shouldn't matter.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
lib/random32.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/lib/random32.c b/lib/random32.c
index 1d6468045267..2c5c3519a0f8 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -118,13 +118,13 @@ void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)
for_each_possible_cpu(i) {
struct rnd_state *state = per_cpu_ptr(pcpu_state, i);
- u32 seeds[4];
- get_random_bytes(&seeds, sizeof(seeds));
- state->s1 = __seed(seeds[0], 2U);
- state->s2 = __seed(seeds[1], 8U);
- state->s3 = __seed(seeds[2], 16U);
- state->s4 = __seed(seeds[3], 128U);
+ get_random_bytes(state, sizeof(state));
+ /* The values must not be near zero. */
+ state->s1 |= 0x100;
+ state->s2 |= 0x100;
+ state->s3 |= 0x100;
+ state->s4 |= 0x100;
prandom_warmup(state);
}
--
2.39.5
prev parent reply other threads:[~2026-11-02 20:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 20:05 [PATCH next 0/7] random32: Improve security and simplify keying David Laight
2026-11-02 20:05 ` [PATCH next 1/7] random32: Improve security of prandom_u32_state() David Laight
2026-11-02 20:05 ` [PATCH next 2/7] random32: Remove some unnecessary #includes David Laight
2026-11-02 20:05 ` [PATCH next 3/7] random32: Fix tests for xor -> add change to prandom_u32_state() David Laight
2026-11-02 20:05 ` [PATCH next 4/7] random32: Change prandom_seed_state() to be a real function David Laight
2026-11-02 20:05 ` [PATCH next 5/7] random32: Use add (not xor) in tools prandom_u32_state() David Laight
2026-11-02 20:05 ` [PATCH next 6/7] random32: prandom_seed_state() use all 64 bits of the seed David Laight
2026-11-02 20:05 ` David Laight [this message]
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