From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 033503B9930; Tue, 21 Jul 2026 22:00:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671238; cv=none; b=iSyepse9gMvfWIMUH8Zf9apipj+oQJVKvgex8Vpxb2EX4ZugW5jjnaV97bJ4oZwS75ssn3s1CJxkZ/dQ023wVF5s2+e7/wz0RievgPbjGShmbo53QIWAnHOizq1rMfghU0S5gq9C1S8TUmpl/RgW0/bP/1KNK+NetIyrAl7c8Gk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671238; c=relaxed/simple; bh=qKz9hGf34IfIy4QrnFAOg7DgIipz/JSSX7oBDf1sWw4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=g8uBTH6t2qNKLfw3pDLFdhJBen8OnuQcTO8WzbwvvmDHw8W4ueonY3bumRX3rU6ckIyQDqxfwIoPl8KOz95sCZKMxf88P9a3nP4NznQrrJ7bES8Z70TrOm2KqPx2h6L//ZPIQVg1ekizm4peJgtVMGLPzlOaIBns1v+vCnC4J/0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FTFOtlsz; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FTFOtlsz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A3031F000E9; Tue, 21 Jul 2026 22:00:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784671236; bh=U+DQEwFJDOrVMAcKCn/PjHYlxKs85YuUBhYtoCqyPG0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=FTFOtlsziRtaZC5zTlyF6f0AduuQfXA4Q2/qpV7lOelGkCWDH7hqte2daxd9e/g5J 0bn6R+9BBS8k/ei3b9r7fAFm03M8t8QfGjE8OEMwY8JFd/+USznbHPiSdFvCT071vP 8Z15ttuSfyc4e/Hlsp0wLL0iA7emrKJyq78Urd6A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Biggers , Herbert Xu Subject: [PATCH 5.15 168/843] crypto: drbg - Fix drbg_max_addtl() on 64-bit kernels Date: Tue, 21 Jul 2026 17:16:43 +0200 Message-ID: <20260721152409.796928363@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit 6f49f00c981bbb9ef602966f19bfdbef46b681d2 upstream. On 64-bit kernels, drbg_max_addtl() returns 2**35 bytes. That's too large, for two reasons: 1. SP800-90A says the maximum limit is 2**35 *bits*, not 2**35 bytes. So the implemented limit has confused bits and bytes. 2. When drbg_kcapi_hash() calls crypto_shash_update() on the additional information string, the length is implicitly cast to 'unsigned int'. That truncates the additional information string to U32_MAX bytes. Fix the maximum additional information string length to always be U32_MAX - 1, causing an error to be returned for any longer lengths. Fixes: 541af946fe13 ("crypto: drbg - SP800-90A Deterministic Random Bit Generator") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- include/crypto/drbg.h | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-) --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -170,19 +170,15 @@ static inline size_t drbg_max_request_by return (1 << 16); } +/* + * SP800-90A allows implementations to support additional info / personalization + * strings of up to 2**35 bits. Implementations can have a smaller maximum. We + * use 2**35 - 16 bits == U32_MAX - 1 bytes so that the max + 1 always fits in a + * size_t, allowing drbg_healthcheck_sanity() to verify its enforcement. + */ static inline size_t drbg_max_addtl(struct drbg_state *drbg) { - /* SP800-90A requires 2**35 bytes additional info str / pers str */ -#if (__BITS_PER_LONG == 32) - /* - * SP800-90A allows smaller maximum numbers to be returned -- we - * return SIZE_MAX - 1 to allow the verification of the enforcement - * of this value in drbg_healthcheck_sanity. - */ - return (SIZE_MAX - 1); -#else - return (1UL<<35); -#endif + return U32_MAX - 1; } static inline size_t drbg_max_requests(struct drbg_state *drbg)