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Miller" Cc: linux-crypto@vger.kernel.org, Eric Biggers , linux-kernel@vger.kernel.org Subject: [PATCH v4 01/10] crypto: Provide a wrapper function for zeroizing crypto_aes_ctx Date: Fri, 7 Aug 2026 09:06:28 +0200 Message-ID: <20260807070651.228713-2-thuth@redhat.com> In-Reply-To: <20260807070651.228713-1-thuth@redhat.com> References: <20260807070651.228713-1-thuth@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 From: Thomas Huth Several crypto drivers need to zeroize their local crypto_aes_ctx structures after use to avoid leaking key material on the stack. Currently some call sites do this with their own memzero_explicit() call, which is error-prone since it is easy to miss a return path (what already happened in some drivers). Some other call sites miss to clear crypto_aes_ctx completely. Provide an aes_zeroize_ctx() helper that can be used with __cleanup() to automatically zeroize the context when it goes out of scope. Acked-by: Eric Biggers Signed-off-by: Thomas Huth --- include/crypto/aes.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/include/crypto/aes.h b/include/crypto/aes.h index 3279cfa546085..eb970b8d623f9 100644 --- a/include/crypto/aes.h +++ b/include/crypto/aes.h @@ -159,6 +159,19 @@ static inline int aes_check_keylen(size_t keylen) int aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key, unsigned int key_len); +/** + * aes_zeroize_ctx - Clear a crypto_aes_ctx structure + * @ctx: The location of the context that should be zeroized + * + * Explicitly fills the crypto_aes_ctx with zeroes. This should be done + * once the context is not required anymore to avoid that its contents + * are leaked on the stack or heap (if not using kfree_sensitive()). + */ +static inline void aes_zeroize_ctx(struct crypto_aes_ctx *ctx) +{ + memzero_explicit(ctx, sizeof(*ctx)); +} + /* * The following functions are temporarily exported for use by the AES mode * implementations in arch/$(SRCARCH)/crypto/. These exports will go away when -- 2.55.0