From patchwork Tue Jul 30 09:40:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 13747150 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B1AAFC3DA61 for ; Tue, 30 Jul 2024 09:42:21 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sYjLP-0003sk-1S; Tue, 30 Jul 2024 05:40:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sYjLN-0003mL-Er for qemu-devel@nongnu.org; Tue, 30 Jul 2024 05:40:33 -0400 Received: from mail-wr1-x42d.google.com ([2a00:1450:4864:20::42d]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1sYjLL-0000cT-IH for qemu-devel@nongnu.org; Tue, 30 Jul 2024 05:40:32 -0400 Received: by mail-wr1-x42d.google.com with SMTP id ffacd0b85a97d-368526b1333so1544766f8f.1 for ; Tue, 30 Jul 2024 02:40:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1722332430; x=1722937230; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=bV8H5RVK0b+LxsupxZcm8cD3g3amlRE8yjf1z8/+Mwk=; b=DDOLs4fdM2IeNlbh6TtmsLdxaGCc84bXoFcunIZCXH8GLagfROfSmSAQHlgHcLObEQ cMcEv+UwP3oAkAynKdgIQ4DhKOc0gSeSEZfAeZj73PpREaViNfFnKwug/qYb4LX/Pbpd zAEKDuFV2ZQPXFevJBuD6fdspbyJ/c1YxhZbZ9pHzRevEzwC8eKrEpBdvkAg6OTaQg2Q OPPNGYsfVY5HR3ZK/qPXMGjgptac5aJggGbBu/0S7gQVXxZJlbaWzSez6p0INIb2IJy9 fwgQZVURLAqi6Fp4DzK4luU/aN0bmSidzPOYZGUrWy6Epknkvi67raNk+mG8GQZBngQh 2zig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722332430; x=1722937230; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=bV8H5RVK0b+LxsupxZcm8cD3g3amlRE8yjf1z8/+Mwk=; b=gdIi5ryp26NT5IA9ZvAfpbQwIumZ9gN5yAdRAE7YlamjeCZAq5KHfKhtDRyobm26Ch GHa/pj5f1gi5d1rU7jtjprfoHEUZZOTvfKi5NlA5Mywin6toTWLsdXVI1CrK36TWdHhr aIrhHUQpdFjHh6txWpnCsVgkrgTqWXDf5Fmq5HaugcOLpOwLcu2C7BCrUrCtz8r4Q7Vc qTIlTMFB2qS52IO9ZTFtEvKXWQwNu/+tjNJhgCTCnBUy4x3++BDYvGR5DQJndl/GEF3f geLm9lIiojwfTer+XDVFqcEIAK11xekRrZTWAjS4IhHZVzTMOvt97Ca07lk71n3vy5mB /KcQ== X-Gm-Message-State: AOJu0Yxl+Sd1sas6t7/72XicMpxlN9f1qwRsdb0B/ifC0wPHh4SdfEIg Kq8hbVQd4X6ERLCbMfeMVA564whglgorARpLrpSSZLq545WAxn2JeVKnQ6b7F1dCXjGiK+h68ms s X-Google-Smtp-Source: AGHT+IGmviJ5DQ+0j9n9zkrKIPgQHyJEZagTewrufB3D7XbyWcVyurnxNTE6679OyWb275vqFpi7Wg== X-Received: by 2002:adf:f549:0:b0:367:8fd9:db6b with SMTP id ffacd0b85a97d-36b8c8df31fmr1081238f8f.9.1722332430071; Tue, 30 Jul 2024 02:40:30 -0700 (PDT) Received: from orth.archaic.org.uk (orth.archaic.org.uk. [2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36b36862549sm14194974f8f.106.2024.07.30.02.40.29 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jul 2024 02:40:29 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Subject: [PULL 14/21] target/arm: Avoid shifts by -1 in tszimm_shr() and tszimm_shl() Date: Tue, 30 Jul 2024 10:40:13 +0100 Message-Id: <20240730094020.2758637-15-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240730094020.2758637-1-peter.maydell@linaro.org> References: <20240730094020.2758637-1-peter.maydell@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::42d; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x42d.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The function tszimm_esz() returns a shift amount, or possibly -1 in certain cases that correspond to unallocated encodings in the instruction set. We catch these later in the trans_ functions (generally with an "a-esz < 0" check), but before we do the decodetree-generated code will also call tszimm_shr() or tszimm_sl(), which will use the tszimm_esz() return value as a shift count without checking that it is not negative, which is undefined behaviour. Avoid the UB by checking the return value in tszimm_shr() and tszimm_shl(). Cc: qemu-stable@nongnu.org Resolves: Coverity CID 1547617, 1547694 Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20240722172957.1041231-4-peter.maydell@linaro.org --- target/arm/tcg/translate-sve.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/target/arm/tcg/translate-sve.c b/target/arm/tcg/translate-sve.c index 798ab2bfb13..a72c2620960 100644 --- a/target/arm/tcg/translate-sve.c +++ b/target/arm/tcg/translate-sve.c @@ -50,13 +50,27 @@ static int tszimm_esz(DisasContext *s, int x) static int tszimm_shr(DisasContext *s, int x) { - return (16 << tszimm_esz(s, x)) - x; + /* + * We won't use the tszimm_shr() value if tszimm_esz() returns -1 (the + * trans function will check for esz < 0), so we can return any + * value we like from here in that case as long as we avoid UB. + */ + int esz = tszimm_esz(s, x); + if (esz < 0) { + return esz; + } + return (16 << esz) - x; } /* See e.g. LSL (immediate, predicated). */ static int tszimm_shl(DisasContext *s, int x) { - return x - (8 << tszimm_esz(s, x)); + /* As with tszimm_shr(), value will be unused if esz < 0 */ + int esz = tszimm_esz(s, x); + if (esz < 0) { + return esz; + } + return x - (8 << esz); } /* The SH bit is in bit 8. Extract the low 8 and shift. */