From patchwork Tue Jan 23 00:26:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13526630 Received: from mail-oo1-f42.google.com (mail-oo1-f42.google.com [209.85.161.42]) (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 DC310157E78 for ; Tue, 23 Jan 2024 00:28:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.42 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705969735; cv=none; b=jZaTe5r1azDBoypcJAZHJWKwxreMuBl2sq0Pwl23D8pcwB1Kl/6O9GNWjbJhBt8gwi9cF/fToV/CxVMQQRabsyVqoUrz6wtOoQVECeT+JPTKVXG3/n8yGXCbx9ZnOGcwYQMWLf9fu4NzwMP4bmDS+ZyYHBgKP8S93lYw/OxeTmY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705969735; c=relaxed/simple; bh=0vuR7p4ixw0RrC8ylPzI4bPxnFYZtvJs/dMTgGJ5vZw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Pg1YG62kmVK7jyqTsFHEfuv0dIlvX7NmlT3SCoMtd+CBzQeMbAkLboudDzMy2G8fJAGuHFTkQN/d4ZN4iMH09i6JkqNTJ6Cf2Dpn4ycKLXnZS4AWqfXcxMXzDaWDqHCm2krnpNWCP8VcRxjX3toB5EscyjHvQyY3Jdji+ikPfnY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=BRNBDGZB; arc=none smtp.client-ip=209.85.161.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="BRNBDGZB" Received: by mail-oo1-f42.google.com with SMTP id 006d021491bc7-598ee012192so1638173eaf.1 for ; Mon, 22 Jan 2024 16:28:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1705969732; x=1706574532; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=+mzYhNEk22l7ZoNe1NF04GNMHFMRe0cWF2yVmwT+ra0=; b=BRNBDGZBMSAU9aDoATTUHu12p7MdSaKxA5X0EYOjPiDMomzyErl5tyrfoZkAvHTAFK k2tVSRquwV4dwqcx+G1nYmapU4n2kMr0FBoG3+1tEFeM9Zm8wNE4TMWOHGKqKxsuyWEF cYpDs0aBE87MIqfRD/EvQJ/eboax76PWm7Epc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705969732; x=1706574532; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=+mzYhNEk22l7ZoNe1NF04GNMHFMRe0cWF2yVmwT+ra0=; b=uEMZBAzERVgUTAK+Rrpd2pJokmOAZuZd3hyslheBFFoLIz/PApOtwOVtXuH9DMrrbZ R9qEMuLbVhHjZ5QcHz2JfEAIxVbxqoyQO94SjuKerjjK0aTgosZx49F5973cLrkHYA6G IqZHHfDP4WD8hlTOttZfyBBMfEyWLGwSx5bDUs+9kaATcZDV6tA7PItoFl+kxChTEXxN 5eQP6BjTilRLVle4ZfST+tebMxHOOiRaAnKkmkeULgwKrz2SVA7EbqitsC26vdjvHdQ9 IVEYVTc3ZRGRHfpEh15EOSYCSMYKFtcO6d1Cd7hh0N9qeyNKyZ/dCKzGWnKLMeuR35+C o0mw== X-Gm-Message-State: AOJu0YxamIZuweysPOFrqJkcmqdA/rPoLtABcQ2tLzeajCnhhs38PSxt OdAT2ABIBE8R9gYrn5fnOgH0D7DZ4ZPCdmfklytGrtQ3H2wDlN67/szZmWfUTA== X-Google-Smtp-Source: AGHT+IEFFCjcvvjDs5VhZZKQMfxmfaEe58OGTZO8rYGeZSl+4Oabsb2rR0IG6UNlABUS+Hoo2bYUkQ== X-Received: by 2002:a05:6358:89c:b0:176:302b:addf with SMTP id m28-20020a056358089c00b00176302baddfmr2445145rwj.11.1705969731980; Mon, 22 Jan 2024 16:28:51 -0800 (PST) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id t3-20020a628103000000b006d842c1eb6fsm10623083pfd.210.2024.01.22.16.28.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jan 2024 16:28:49 -0800 (PST) From: Kees Cook To: linux-hardening@vger.kernel.org Cc: Kees Cook , Wu Hao , Tom Rix , Moritz Fischer , Xu Yilun , linux-fpga@vger.kernel.org, "Gustavo A. R. Silva" , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org Subject: [PATCH 20/82] fpga: dfl: Refactor intentional wrap-around calculation Date: Mon, 22 Jan 2024 16:26:55 -0800 Message-Id: <20240123002814.1396804-20-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240122235208.work.748-kees@kernel.org> References: <20240122235208.work.748-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-fpga@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2215; i=keescook@chromium.org; h=from:subject; bh=0vuR7p4ixw0RrC8ylPzI4bPxnFYZtvJs/dMTgGJ5vZw=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlrwgGHtjsSSN/FMeEK+eLhH3Rf2IQ7QXdGbQOh GLaFivRK7SJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZa8IBgAKCRCJcvTf3G3A JjwFEACq/xltKSW9/AcV8nURH4w+OhwZyCA5rN6lx9nRT19Yrrpsyh46ZacM7qLIRfXPyb9Wd+q W/ZaxHD6dec3ZWn2vr6dNx/S+6JulWL69SBFoD/Nui8MMG67egljBLYBcYz0NnTxdUaEovsRTjs 00TCrQdq8uFVTCZ6uIY4TiHMPbUNMZSIsloMUE3cCSpElU7skC9RHl61eYgW3OZmEsMsFvxzNhS tSy6oEkp4ETYdA1qEZq5V7aiH2rIziK7CNNrYg5GM1xUrqRTAikI8yponLWEPC0Dm5IDWnB6ong LiLqB0xMeQYRH8YCAJLBZB5KVyHCESLS6n26/HQaNYaMcbMYmOCTuboxWSCxaJiz3OkSuxqErlH gpN5tMaUpGQzYwm39f2CsadQgOfSyR7i+g9+pFDdfY5st1jylp+v8o+Xc+b9M8gasnUpNSMyBKC i/KFVGgFOBzwf/a/iMqg81pPkTDiic9cMAzjQAni6b2u5Itiad2QmvNntQb8BMkqbhPwTMPJ8HB AMTt1Ok+GwJ+55EPC7JPQC73k/jEvTR3KlvYL98PqXom6c/pD+V9a1jSgu8JGydxhunOYziZ8Fm nCglfYM7BRv+8zjUyvboX5/hptVcbwqXJuzoAzMJd4vXJpZFuQ+bjhaph5jUnAq3ffbU6UEpTRw /dzTrO4kzPwetig== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 In an effort to separate intentional arithmetic wrap-around from unexpected wrap-around, we need to refactor places that depend on this kind of math. One of the most common code patterns of this is: VAR + value < VAR Notably, this is considered "undefined behavior" for signed and pointer types, which the kernel works around by using the -fno-strict-overflow option in the build[1] (which used to just be -fwrapv). Regardless, we want to get the kernel source to the position where we can meaningfully instrument arithmetic wrap-around conditions and catch them when they are unexpected, regardless of whether they are signed[2], unsigned[3], or pointer[4] types. Refactor open-coded unsigned wrap-around addition test to use check_add_overflow(), retaining the result for later usage (which removes the redundant open-coded addition). This paves the way to enabling the wrap-around sanitizers in the future. Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] Link: https://github.com/KSPP/linux/issues/26 [2] Link: https://github.com/KSPP/linux/issues/27 [3] Link: https://github.com/KSPP/linux/issues/344 [4] Cc: Wu Hao Cc: Tom Rix Cc: Moritz Fischer Cc: Xu Yilun Cc: linux-fpga@vger.kernel.org Signed-off-by: Kees Cook --- drivers/fpga/dfl.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c index e6d12fbab653..7d10780e3a98 100644 --- a/drivers/fpga/dfl.c +++ b/drivers/fpga/dfl.c @@ -1939,15 +1939,16 @@ static int do_set_irq_trigger(struct dfl_feature *feature, unsigned int idx, int dfl_fpga_set_irq_triggers(struct dfl_feature *feature, unsigned int start, unsigned int count, int32_t *fds) { + unsigned int sum; unsigned int i; int ret = 0; /* overflow */ - if (unlikely(start + count < start)) + if (unlikely(check_add_overflow(start, count, &sum))) return -EINVAL; /* exceeds nr_irqs */ - if (start + count > feature->nr_irqs) + if (sum > feature->nr_irqs) return -EINVAL; for (i = 0; i < count; i++) {