linux-kernel - [PATCH] crypto: sun8i-ce - use kfree_sensitive to clear and free sensitive data

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Date:   Tue,  3 Aug 2021 20:55:25 +0800
From:   Jason Wang <wangborong@...rlc.com>
To:     herbert@...dor.apana.org.au
Cc:     clabbe.montjoie@...il.com, davem@...emloft.net, mripard@...nel.org,
        wens@...e.org, jernej.skrabec@...il.com, wangborong@...rlc.com,
        mchehab+huawei@...nel.org, corbet@....net, baijiaju1990@...il.com,
        linux-crypto@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH] crypto: sun8i-ce - use kfree_sensitive to clear and free sensitive data

The kfree_sensitive is a kernel API to clear sensitive information
that should not be leaked to other future users of the same memory
objects and free the memory. Its function is the same as the
combination  of memzero_explicit and kfree. Thus, we can replace the
combination APIs with the single kfree_sensitive API.

Signed-off-by: Jason Wang <wangborong@...rlc.com>
---
 drivers/crypto/allwinner/sun8i-ce/sun8i-ce-prng.c | 9 +++------
 drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c | 3 +--
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-prng.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-prng.c
index cd1baee424a1..b3a9bbfb8831 100644
--- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-prng.c
+++ b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-prng.c
@@ -26,8 +26,7 @@ void sun8i_ce_prng_exit(struct crypto_tfm *tfm)
 {
 	struct sun8i_ce_rng_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 
-	memzero_explicit(ctx->seed, ctx->slen);
-	kfree(ctx->seed);
+	kfree_sensitive(ctx->seed);
 	ctx->seed = NULL;
 	ctx->slen = 0;
 }
@@ -38,8 +37,7 @@ int sun8i_ce_prng_seed(struct crypto_rng *tfm, const u8 *seed,
 	struct sun8i_ce_rng_tfm_ctx *ctx = crypto_rng_ctx(tfm);
 
 	if (ctx->seed && ctx->slen != slen) {
-		memzero_explicit(ctx->seed, ctx->slen);
-		kfree(ctx->seed);
+		kfree_sensitive(ctx->seed);
 		ctx->slen = 0;
 		ctx->seed = NULL;
 	}
@@ -157,9 +155,8 @@ int sun8i_ce_prng_generate(struct crypto_rng *tfm, const u8 *src,
 		memcpy(dst, d, dlen);
 		memcpy(ctx->seed, d + dlen, ctx->slen);
 	}
-	memzero_explicit(d, todo);
 err_iv:
-	kfree(d);
+	kfree_sensitive(d);
 err_mem:
 	return err;
 }
diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c
index 5b7af4498bd5..19cd2e52f89d 100644
--- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c
+++ b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-trng.c
@@ -95,9 +95,8 @@ static int sun8i_ce_trng_read(struct hwrng *rng, void *data, size_t max, bool wa
 		memcpy(data, d, max);
 		err = max;
 	}
-	memzero_explicit(d, todo);
 err_dst:
-	kfree(d);
+	kfree_sensitive(d);
 	return err;
 }
 
-- 
2.32.0