From patchwork Fri Nov 24 02:03:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Su Hui X-Patchwork-Id: 13466882 X-Patchwork-Delegate: kvalo@adurom.com Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from mail.nfschina.com (unknown [42.101.60.195]) by lindbergh.monkeyblade.net (Postfix) with SMTP id 47071D72; Thu, 23 Nov 2023 18:04:33 -0800 (PST) Received: from localhost.localdomain (unknown [180.167.10.98]) by mail.nfschina.com (Maildata Gateway V2.8.8) with ESMTPSA id 55569602610F3; Fri, 24 Nov 2023 10:04:25 +0800 (CST) X-MD-Sfrom: suhui@nfschina.com X-MD-SrcIP: 180.167.10.98 From: Su Hui To: dan.carpenter@linaro.org, pkshih@realtek.com, kvalo@kernel.org, nathan@kernel.org, ndesaulniers@google.com, trix@redhat.com Cc: Su Hui , lizetao1@huawei.com, linville@tuxdriver.com, Larry.Finger@lwfinger.net, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, kernel-janitors@vger.kernel.org Subject: [PATCH v2 2/2] wifi: rtlwifi: rtl8821ae: phy: fix an undefined bitwise shift behavior Date: Fri, 24 Nov 2023 10:03:54 +0800 Message-Id: <20231124020352.1660621-2-suhui@nfschina.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20231124020352.1660621-1-suhui@nfschina.com> Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Clang staic checker warning: drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c:184:49: The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'u32'. [core.UndefinedBinaryOperatorResult] If the value of the right operand is negative or is greater than or equal to the width of the promoted left operand, the behavior is undefined.[1][2] For example, when using different gcc's compilation optimizaation options (-O0 or -O2), the result of '(u32)data << 32' is different. One is 0, the other is old value of data. Let _rtl8821ae_phy_calculate_bit_shift()'s return value less than 32 to fix this problem. Warn if bitmask is zero. [1]:https://stackoverflow.com/questions/11270492/what-does-the-c- standard-say-about-bitshifting-more-bits-than-the-width-of-type [2]:https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf Fixes: 21e4b0726dc6 ("rtlwifi: rtl8821ae: Move driver from staging to regular tree") Signed-off-by: Su Hui --- v2: - fix the subject prefix problem - silence the warning by not return 32 bits rather than adding a type cast.(Thanks to Dan and Ping-Ke) By the way, there some similar problems in _rtl88e_phy_calculate_bit_shift(), _rtl92c_phy_calculate_bit_shift() and so on... drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c index 6df270e29e66..52ab1b0761c0 100644 --- a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c @@ -31,7 +31,12 @@ static u32 _rtl8821ae_phy_calculate_bit_shift(u32 bitmask) { u32 i = ffs(bitmask); - return i ? i - 1 : 32; + if (!i) { + WARN_ON_ONCE(1); + return 0; + } + + return i - 1; } static bool _rtl8821ae_phy_bb8821a_config_parafile(struct ieee80211_hw *hw); /*static bool _rtl8812ae_phy_config_mac_with_headerfile(struct ieee80211_hw *hw);*/