From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f52.google.com (mail-ej1-f52.google.com [209.85.218.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20146372070 for ; Fri, 10 Jul 2026 17:29:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783704579; cv=none; b=VY8QYY845BFEXpcpINVx+UTseZ410cK0pdNTWt7HoE2g7/1G/tNuEYjVnmIDpX9XkLJNqcY4LBnlgcWg4VzHCFJtXOFG+TzZORV0AQ94e81ZW7zPNs4TV1X7zfqODCXJIUa2grIYv+AlDyZm5X4dgSx0gSX+Vuivi5FvpMT/NPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783704579; c=relaxed/simple; bh=sHYhG4DNygGPej0hSQJB/7SJr7cdvMyQNw2AVk0hPhA=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=s3cXR8ddOLNjxC1sx2o5EMf1c+aVVeqZsUkKK43+GQFAG5YUh5llxYYHuv7MXRm5FSeu3AIEUySCUZblz1cQBvNNqK0ZbsdJ24sAqisfJ22ZI3QSiMYHFj4CQhJ0rI3BbpC3+06Mot8tn0yBkHOr8mAV1N8b6VhZcO6dSScEjkY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=googlemail.com; spf=pass smtp.mailfrom=googlemail.com; dkim=pass (2048-bit key) header.d=googlemail.com header.i=@googlemail.com header.b=I6LlpBKd; arc=none smtp.client-ip=209.85.218.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=googlemail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=googlemail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=googlemail.com header.i=@googlemail.com header.b="I6LlpBKd" Received: by mail-ej1-f52.google.com with SMTP id a640c23a62f3a-c15d3cd51b2so144857766b.3 for ; Fri, 10 Jul 2026 10:29:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20251104; t=1783704576; x=1784309376; darn=vger.kernel.org; h=content-disposition:content-type:mime-version:message-id:subject:cc :to:from:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=yM6C7TqLs0ysaf4+YV06Fpssphvvfjwqj9luc4OgHeg=; b=I6LlpBKd0tJRxZZtlZC/rZlIpgslOWqHEpF0Tzmn4482m3DEBaPQIDUByWHJLVZeMV +ZVEhVqqvbuwGvj4wycTQzfrhxhEw/hz0xqaXD2DTcAv06YI45H2TcUERYL/pn6IM9BV tMpZAnRhK5SADEaTlqX+BV2TcjhucsgRUjhTfhEq8/0qBJdMdrBoVVKb7Zl+wbFD8Cl9 yKzfMPmZPIp1oq+nsR9922Nzw7IFHa1QonR4Xgu6xju07PD08XVCQ0+AbFZDV3gIGK65 75hw2QmTp4qAi9Fw/II09Fkf4Snz04MYsJSMRDxNvpQEUUrGJz7u/i9wdqwyZHNsENVj kq3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1783704576; x=1784309376; h=content-disposition:content-type:mime-version:message-id:subject:cc :to:from:date:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=yM6C7TqLs0ysaf4+YV06Fpssphvvfjwqj9luc4OgHeg=; b=rEGhpMiiL8QeNzuQkrlnJXpAd5us6rOzZBUsSCxKzuFJ/+zsu+smiG5gKoOPY821lW BRtkWyT1GXokRMaF6EJEhoXjWPeGEyqliPwJL+4bdDM9b0nCFSqSQ6w1nQOX7e7rDbf3 kaH+uT0b/L14SVmbsljZyh9g8Q/Ir3lRtMrO0ZUglZYxBwVcn8B92yishkkbbLKnR7rl pLoDXyA5UKtIFGghRpzqFk5m5lrpebqjTEwWOXMQSWenkaeEsogNAdmBDeXAa7NYQjyv fPsZUWI0O7N25/wljFErE5m8GK6yQ3TGLv2HCTug2TM/bEWLWhyL4qzyOnYE8psjuzDt C0qw== X-Forwarded-Encrypted: i=1; AHgh+RoiMGROue+iJx8odXw+x7bEtagJuHAm/9s1gJZ6rbngq2u+Z2t5omjGZ+5sek/HAo9f1y54telXOW5e82M=@vger.kernel.org X-Gm-Message-State: AOJu0Yx0Hq5+pPR786+5pNUfMEEuy1YaI+0HP55EzoRD5eJ5XgB56YGx RFMeeB1rsjWBcodYbdDsRD9Krg+c4MvCa8QBZr3PRV3zQ2u9UFQpubMm X-Gm-Gg: AfdE7cm0WCD7lvoFU6N9wyyoGbLx1mzhG7FjjWh5wy4JoYbAW0XhBl0/Kryw4lVH7HB Gp4A2vAGyh+S4eMGCpGMDVyRwH4UsEyT2ciyDrt5dZtnB5INpB/arH+jozVenER804Xwj1wY0ew qltKEj1egvF6hQ0pUPh+IPMPUQlsLRf20s9+ZVrApCMTNN2q0kGUHjo9AJkpLPa83cWtzir5Gq5 Gwt6iCL6Dre/aa/ALUzSg24pqd/Mspe31EifB+6bw3+xZqbR7aCIym5fur8B/Yb1wIbKKbNRzlZ zr/6+3e/erz8slZYNpxBO+Y3rSWn+5akg6OlMpPKar+nsY8QUW7oip0cnbRQTNuiIrGwU0Q8fut ervqAixpfK6eltVb1TBFRdTL8z605tGkVT1nEUZfdQF044f/TdvxEMPObZnz3/9rae0ABGtFL2N cXg7WnLPd4ZHUXWfjEy9i6vXyjNpFyGva+UZYoCgUI X-Received: by 2002:a17:907:9713:b0:c16:9bd:39cc with SMTP id a640c23a62f3a-c1609bd3edfmr119069666b.5.1783704576367; Fri, 10 Jul 2026 10:29:36 -0700 (PDT) Received: from fudgebox (k10193.upc-k.chello.nl. [62.108.10.193]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c15bc428775sm581447866b.6.2026.07.10.10.29.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2026 10:29:35 -0700 (PDT) Date: Fri, 10 Jul 2026 19:29:33 +0200 From: "David C.C.M. Gall" To: Lukas Wunner , Ignat Korchagin , Herbert Xu , "David S. Miller" , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Cc: gregkh@linuxfoundation.org Subject: [PATCH] crypto: rsassa-pkcs1: use constant-time comparison for digest and signature verification Message-ID: Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Replace memcmp() with crypto_memneq() for cryptographic digest and signature comparisons to prevent timing side-channel attacks. crypto/rsassa-pkcs1.c: RSA signature digest verification used memcmp which can leak valid prefix length via timing analysis, user data could reach the leaky comparison via the digest argument to verify. Assisted-by: gregkh_clanker_t1000 Signed-off-by: David C.C.M. Gall --- crypto/rsassa-pkcs1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/crypto/rsassa-pkcs1.c b/crypto/rsassa-pkcs1.c index 94fa5e9600e7..a612a9eef2dd 100644 --- a/crypto/rsassa-pkcs1.c +++ b/crypto/rsassa-pkcs1.c @@ -291,7 +291,7 @@ static int rsassa_pkcs1_verify(struct crypto_sig *tfm, /* RFC 8017 sec 8.2.2 step 4 - comparison of digest with out_buf */ if (dlen != dst_len - pos) return -EKEYREJECTED; - if (memcmp(digest, out_buf + pos, dlen) != 0) + if (crypto_memneq(digest, out_buf + pos, dlen)) return -EKEYREJECTED; return 0; -- 2.43.0