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Donenfeld" , Ard Biesheuvel Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] lib/crypto: chacha20poly1305: Clear chacha_state in xchacha20poly1305_decrypt() Date: Thu, 13 Aug 2026 15:01:47 +0200 Message-ID: <20260813130147.949545-1-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 10.30.177.93 From: Thomas Huth The chacha20poly1305_decrypt() already clears it chacha_state at the end, so xchacha20poly1305_decrypt() should do the same, too, to avoid leaking sensitive information on the stack. Use a __cleanup() marker to avoid that we have to do it manually here. For symmetry, use the __cleanup() marker in chacha20poly1305_decrypt(), too. Signed-off-by: Thomas Huth --- lib/crypto/chacha20poly1305.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/lib/crypto/chacha20poly1305.c b/lib/crypto/chacha20poly1305.c index ea42a28f4ff7d..b40377dca8e02 100644 --- a/lib/crypto/chacha20poly1305.c +++ b/lib/crypto/chacha20poly1305.c @@ -172,7 +172,7 @@ bool chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len, const u64 nonce, const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) { - struct chacha_state chacha_state; + struct chacha_state chacha_state __cleanup(chacha_zeroize_state); u32 k[CHACHA_KEY_WORDS]; __le64 iv[2]; bool ret; @@ -186,7 +186,6 @@ bool chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len, ret = __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len, &chacha_state); - chacha_zeroize_state(&chacha_state); memzero_explicit(iv, sizeof(iv)); memzero_explicit(k, sizeof(k)); return ret; @@ -198,7 +197,7 @@ bool xchacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len, const u8 nonce[at_least XCHACHA20POLY1305_NONCE_SIZE], const u8 key[at_least CHACHA20POLY1305_KEY_SIZE]) { - struct chacha_state chacha_state; + struct chacha_state chacha_state __cleanup(chacha_zeroize_state); xchacha_init(&chacha_state, key, nonce); return __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len, -- 2.55.0