linux-kernel - [PATCH 3/6] hw_random: use rng_fillbuf in add_early

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Message-Id: <20220124202951.28579-3-linux@dominikbrodowski.net>
Date:   Mon, 24 Jan 2022 21:29:48 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        "Jason A . Donenfeld" <Jason@...c4.com>
Subject: [PATCH 3/6] hw_random: use rng_fillbuf in add_early_randomness()

Using rng_buffer in add_early_randomness() may race with rng_dev_read().
Use rng_fillbuf instead, as it is otherwise only used within the kernel
by hwrng_fillfn() and therefore never exposed to userspace.

Cc: Matt Mackall <mpm@...enic.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Jason A. Donenfeld <Jason@...c4.com>
Signed-off-by: Dominik Brodowski <linux@...inikbrodowski.net>
---
 drivers/char/hw_random/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index c2d260b5dd92..89891ac87af0 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -66,10 +66,10 @@ static void add_early_randomness(struct hwrng *rng)
 	int bytes_read;
 
 	mutex_lock(&reading_mutex);
-	bytes_read = rng_get_data(rng, rng_buffer, 32, 0);
+	bytes_read = rng_get_data(rng, rng_fillbuf, 32, 0);
 	mutex_unlock(&reading_mutex);
 	if (bytes_read > 0)
-		add_device_randomness(rng_buffer, bytes_read);
+		add_device_randomness(rng_fillbuf, bytes_read);
 }
 
 static inline void cleanup_rng(struct kref *kref)
-- 
2.34.1