From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 955ED36166E; Tue, 10 Mar 2026 19:52:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773172371; cv=none; b=fOForn80ws4Re3DHyQhkVLFzYKFjcMSq0NEZlPwCidkHKxL0dfpVLElt89tXljxG18iXhTD6hvLB6EHepCzyo/50F33eVDez3RM8m0vZNL55Anz3qyu8Z8FwWZOQIV1Yq15r2Hafrj9p+dxFRfXrf4ob9NmLH8UhO95gfx5tBbE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773172371; c=relaxed/simple; bh=ZljlsaZrVSABj0WGZEN8HZRXYNDW4ztD1TIc/UZ7+Kk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=BqzMk62YnndS5p4Nes3fcxusufnm+2jmsUK7ecsaXs+Bj+r60+YK8wGMIgWdXvvazUrjhnwWxerptyuYxAtE/QMHI2+zSjhfewpedMVWvYs5JH++iVSFb7vmz5zfcQVcIUlDQkN8t0CHoPrsa0a0/+ugBYBevUONKYni+/cQTpY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cs6MPMmG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Cs6MPMmG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F7C0C19425; Tue, 10 Mar 2026 19:52:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773172371; bh=ZljlsaZrVSABj0WGZEN8HZRXYNDW4ztD1TIc/UZ7+Kk=; h=From:To:Cc:Subject:Date:From; b=Cs6MPMmGHMYfD/AiCuUY7uIQLSIDd3Z2gPNs8zfogm2eus4YkCknrocxGIlCVzY0A KZwvvhir7j/VevZm9IJI3okcHQFUzmRwL0NCa1hJQ19Ej4SWIik4iEU2gZBgxQUPe9 IY5C4gTEl/pzLueiu4WBGnbBUwvT2oAGfuJeubJfcj1LSr2MBJybXL2PQF6HlAhcFK fShxnCVKqKrtqxljPVxswzOwwRofVCV7LY/eegI5tguQKwpHdML06XgoSiBZ5iOte2 fdkdiVHaMVLYrkdZkGpkOcO6D1qxJTHmUWaZ6EqSo7jGKOZhifKeuFUTN94Y1FN3e2 yYHUVbpClmbUQ== From: Eric Biggers To: stable@vger.kernel.org Cc: linux-crypto@vger.kernel.org, linux-cifs@vger.kernel.org, Eric Biggers , Namjae Jeon , Steve French Subject: [PATCH 6.18] ksmbd: Compare MACs in constant time Date: Tue, 10 Mar 2026 12:52:14 -0700 Message-ID: <20260310195214.70843-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit commit c5794709bc9105935dbedef8b9cf9c06f2b559fa upstream. To prevent timing attacks, MAC comparisons need to be constant-time. Replace the memcmp() with the correct function, crypto_memneq(). Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Acked-by: Namjae Jeon Signed-off-by: Steve French --- fs/smb/server/Kconfig | 1 + fs/smb/server/auth.c | 4 +++- fs/smb/server/smb2pdu.c | 5 +++-- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/Kconfig b/fs/smb/server/Kconfig index 098cac98d31e6..6200c71298f66 100644 --- a/fs/smb/server/Kconfig +++ b/fs/smb/server/Kconfig @@ -11,10 +11,11 @@ config SMB_SERVER select CRYPTO_HMAC select CRYPTO_ECB select CRYPTO_LIB_ARC4 select CRYPTO_LIB_DES select CRYPTO_LIB_SHA256 + select CRYPTO_LIB_UTILS select CRYPTO_SHA256 select CRYPTO_CMAC select CRYPTO_SHA512 select CRYPTO_AEAD2 select CRYPTO_CCM diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c index b4020bb55a268..f92b2f3dc6de0 100644 --- a/fs/smb/server/auth.c +++ b/fs/smb/server/auth.c @@ -11,10 +11,11 @@ #include #include #include #include #include +#include #include #include #include "auth.h" #include "glob.h" @@ -281,11 +282,12 @@ int ksmbd_auth_ntlmv2(struct ksmbd_conn *conn, struct ksmbd_session *sess, if (rc) { ksmbd_debug(AUTH, "Could not generate sess key\n"); goto out; } - if (memcmp(ntlmv2->ntlmv2_hash, ntlmv2_rsp, CIFS_HMAC_MD5_HASH_SIZE) != 0) + if (crypto_memneq(ntlmv2->ntlmv2_hash, ntlmv2_rsp, + CIFS_HMAC_MD5_HASH_SIZE)) rc = -EINVAL; out: if (ctx) ksmbd_release_crypto_ctx(ctx); kfree(construct); diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index bf8c480594367..f82d6c6b94101 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2,10 +2,11 @@ /* * Copyright (C) 2016 Namjae Jeon * Copyright (C) 2018 Samsung Electronics Co., Ltd. */ +#include #include #include #include #include #include @@ -8879,11 +8880,11 @@ int smb2_check_sign_req(struct ksmbd_work *work) if (ksmbd_sign_smb2_pdu(work->conn, work->sess->sess_key, iov, 1, signature)) return 0; - if (memcmp(signature, signature_req, SMB2_SIGNATURE_SIZE)) { + if (crypto_memneq(signature, signature_req, SMB2_SIGNATURE_SIZE)) { pr_err("bad smb2 signature\n"); return 0; } return 1; @@ -8967,11 +8968,11 @@ int smb3_check_sign_req(struct ksmbd_work *work) iov[0].iov_len = len; if (ksmbd_sign_smb3_pdu(conn, signing_key, iov, 1, signature)) return 0; - if (memcmp(signature, signature_req, SMB2_SIGNATURE_SIZE)) { + if (crypto_memneq(signature, signature_req, SMB2_SIGNATURE_SIZE)) { pr_err("bad smb2 signature\n"); return 0; } return 1; base-commit: 6258e292d7463f96d0f06dff2a39093a54c9d16f -- 2.53.0