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 A10D147010D; Tue, 21 Jul 2026 20:23:52 +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=1784665433; cv=none; b=A4SoHYWL9aWUoDznMapoA2OR+SxgOeMDfQS9gdpaA9KRrti93nk+OGoMUGSYR57EAXnarP2DZAoSeFVx3pDYzaQ5+HWxHdNaPoHc9RjMw3dupf2B9k+nGFnFs+i/fhZNNl2zKUJ2feR4+auj96YK7z7c1YsdU5To3D8SmvvIFsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665433; c=relaxed/simple; bh=3/aN/ZkEL5DLUoHDNVHTKhbk5KodtDRTraJefrCQ8lw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cQ0d1UQwPlDNhFgQPR3Su5J2ahFYejQ5veLIPe7UuCffARmeEAiq1ZqK08d+c8Ux4QUhlWnqPKDRLqzEuGQ5re/jFehNQdFFMj1mefXUxE05zjzCE8Sb+YQRKuJyzOAcbw4qZ9CR/63x3m3exOmR3yXmQ4F25Sz0DtHxihIsjHg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=b+1dhaL8; 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="b+1dhaL8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 133001F000E9; Tue, 21 Jul 2026 20:23:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784665432; bh=pqtciEkaVoRHdoXd0MECVRO/yLODODsIFoNpCqMO33s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=b+1dhaL8QpKrj2NWsHks/rGd/2vRYoHT59axZ7aiUb4nToRVrV+Y/uVL9Hl37tFEx 9Yh47c+jRBMOrxCmDRKuUB5aoAJnvZAdgKa1aUQbFsahuHvPaPGg5bcV4OaHkq5kiK DuIrH8kH+jU5XNHVn+gBG1lyBJ/Xs7OHJy5gosJM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Biggers , Herbert Xu Subject: [PATCH 6.6 0275/1266] crypto: drbg - Fix drbg_max_addtl() on 64-bit kernels Date: Tue, 21 Jul 2026 17:11:52 +0200 Message-ID: <20260721152447.976795109@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-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 @@ -171,19 +171,15 @@ 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)