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Miller" , "Jason A. Donenfeld" , Ard Biesheuvel , Borislav Petkov Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Dave Hansen Subject: [PATCH v4 02/13] lib/crypto: aes-xts: Provide function for zeroizing aes_xts_key Date: Wed, 16 Sep 2026 11:50:04 +0200 Message-ID: <20260916095022.604354-3-thuth@redhat.com> In-Reply-To: <20260916095022.604354-1-thuth@redhat.com> References: <20260916095022.604354-1-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 3.4.1 on 10.30.177.111 In certain cases crypto code functions need to zeroize their local aes_xts_key structures after use to avoid leaking sensitive material. Provide an aes_xts_zeroize_key() helper function that e.g. can be used with __cleanup() to automatically zeroize the struct when it goes out of scope. While we're at it, replace the related memzero_explicit() call in lib/crypto/aes.c with a call to the new helper function. Signed-off-by: Thomas Huth --- include/crypto/aes-xts.h | 13 +++++++++++-- lib/crypto/aes.c | 2 +- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/include/crypto/aes-xts.h b/include/crypto/aes-xts.h index b9e828265e58a..3a52e1cf40b57 100644 --- a/include/crypto/aes-xts.h +++ b/include/crypto/aes-xts.h @@ -22,6 +22,15 @@ struct aes_xts_key { struct aes_enckey tweak_key; }; +/** + * aes_xts_zeroize_key() - Zeroize an aes_xts_key structure + * @key: The aes_xts_key to zeroize + */ +static inline void aes_xts_zeroize_key(struct aes_xts_key *key) +{ + memzero_explicit(key, sizeof(*key)); +} + /** * aes_xts_preparekey() - Prepare a key for AES-XTS encryption and decryption * @key: (output) The key structure to initialize @@ -30,8 +39,8 @@ struct aes_xts_key { * @flags: Optional flag XTS_FORBID_WEAK_KEYS to forbid keys whose two halves * are the same. * - * Users should use memzero_explicit() to zeroize the key struct at the end of - * its lifetime. (But if this function fails, zeroization is unnecessary.) + * Users should use aes_xts_zeroize_key() to zeroize the key struct at the end + * of its lifetime. (But if this function fails, zeroization is unnecessary.) * * Context: Any context. * Return: diff --git a/lib/crypto/aes.c b/lib/crypto/aes.c index 07c1d912ac365..34ef5deca0a79 100644 --- a/lib/crypto/aes.c +++ b/lib/crypto/aes.c @@ -1223,7 +1223,7 @@ int aes_xts_preparekey(struct aes_xts_key *key, const u8 *in_key, return 0; out_zeroize: - memzero_explicit(key, sizeof(*key)); + aes_xts_zeroize_key(key); return err; } EXPORT_SYMBOL_GPL(aes_xts_preparekey); -- 2.55.0