linux-kernel - [v2 PATCH] crypto: drbg - Delete unused ctx from struct sdesc

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Message-ID: <aR1JvnpTBomcKAMZ@gondor.apana.org.au>
Date: Wed, 19 Nov 2025 12:38:22 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
	Stephan Mueller <smueller@...onox.de>
Subject: [v2 PATCH] crypto: drbg - Delete unused ctx from struct sdesc

On Mon, Nov 10, 2025 at 07:44:56PM +0900, Gustavo A. R. Silva wrote:
>
> diff --git a/crypto/drbg.c b/crypto/drbg.c
> index 511a27c91813..e9f9775c237f 100644
> --- a/crypto/drbg.c
> +++ b/crypto/drbg.c
> @@ -1442,9 +1442,12 @@ static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
>  
>  #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
>  struct sdesc {
> -	struct shash_desc shash;
> -	char ctx[];
> +	/* Must be last as it ends in a flexible-array member. */
> +	TRAILING_OVERLAP(struct shash_desc, shash, __ctx,
> +		char ctx[];
> +	);
>  };
> +static_assert(offsetof(struct sdesc, shash.__ctx) == offsetof(struct sdesc, ctx));

This isn't even used.  Just delete it:

---8<---
The ctx array in struct sdesc is never used.  Delete it as it's
bogus since the previous member ends with a flexible array.

Reported-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 511a27c91813..1d433dae9955 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1443,7 +1443,6 @@ static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
 struct sdesc {
 	struct shash_desc shash;
-	char ctx[];
 };
 
 static int drbg_init_hash_kernel(struct drbg_state *drbg)
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt