From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f43.google.com (mail-lf1-f43.google.com [209.85.167.43]) (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 DCE783FC2 for ; Thu, 26 Aug 2021 20:03:08 +0000 (UTC) Received: by mail-lf1-f43.google.com with SMTP id b4so9257112lfo.13 for ; Thu, 26 Aug 2021 13:03:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=3zAr+cyoXevrt8A+DyLi9G7nlDrM3xPW3HSqFrbuWPs=; b=Icip//QmnD0NfBJVT3jKI5SpPllcAFbvQJPqcqAi/lHASsMeGAYEwhsLQR1iq41S45 jOzXGIyTUMc62f3JOHJTfpjSW5XWDpkfcUfBeITDpzkUaTuU/1q9ATb8uk3E5i8CN5T3 0AzphqxcD6CPlGJHUvhLW9FDkqc46Omn/SmjptA5Qxix8Nm7rgrf0L4sWvYVA+l5Tp0i g8bmd5FMM7T4LTuKvUSwuM32w7/mA0jDmWIxmcwUsXaOwnk1fTLA2XK15KaBdJgArb2H A5vS22SK2seRm8qqMYfJL3pU6v3Ci4+zwOypaTIvI1o/RIMOTYZ7RkJv8xG1H3WfB7uh BYFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=3zAr+cyoXevrt8A+DyLi9G7nlDrM3xPW3HSqFrbuWPs=; b=XMSrLh2JRFIlIsNUymF0Oblnf1HcfOcjgquKUthcO2F2Nb7AQP8r3++ZVGde8CT8jI M5e/IWVFfbMZVHJaxVIyscVwGutyWkCovARfWD/wKhIMox5DBzd40tijpd+Gy2dyVJRM NWSeCDD4uvBjMk6ecLfmYrgixiYHD5Cm0aHsV4qsRyh7DPVgr1qTBJzQ/L08hSzQNr9T F13t+5oTUC3jzeAGqN1LH3Rti7wr2/mPVjbpkXT4nHgdCTod1GIrqOmtRj0XB3vI2l4X FgYKIM0iR99D//NBXWJtRdfIIwkBIuOSqlmhwjCm9I1PuSB6eI3Kep7/8cWBH5K/gb2N rKwQ== X-Gm-Message-State: AOAM531tlc8ap9YqWK5LWXbH8bGiwIh3jnb92ECGQt4Q6uV48p5LTekD Y6D08FNO2GS2Y+wuiSAhkC0= X-Google-Smtp-Source: ABdhPJzFUVFuXxfr49qDXFQHyBkAbZDK+s8QKVlAGiVJEju4KP3Zu+mi5R4agrFlZpcWYZPZOxqXCA== X-Received: by 2002:ac2:41d9:: with SMTP id d25mr3921380lfi.386.1630008186989; Thu, 26 Aug 2021 13:03:06 -0700 (PDT) Received: from [192.168.1.11] ([46.235.66.127]) by smtp.gmail.com with ESMTPSA id b4sm397722lfo.94.2021.08.26.13.03.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Aug 2021 13:03:06 -0700 (PDT) Subject: Re: [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32 To: David Laight Cc: "Larry.Finger@lwfinger.net" , "phil@philpotter.co.uk" , "gregkh@linuxfoundation.org" , "straube.linux@gmail.com" , "fmdefrancesco@gmail.com" , "linux-staging@lists.linux.dev" , "linux-kernel@vger.kernel.org" References: <93bf46ce2d0ce12e94672acf28b64dc341fde038.1629789580.git.paskripkin@gmail.com> <27f5e52d520b453cbcabb3d72f0f5d15@AcuMS.aculab.com> <20210826122221.5d2b0f37@gmail.com> <685618ac-8de1-4eb1-57dd-9d43b96e872e@gmail.com> <64112dfd8e8b472ab78ca8b4837dc9e9@AcuMS.aculab.com> <0eb2bbc6-9d35-9ff3-acde-fd89bbe0ca27@gmail.com> <6e864f9d133d4db3923190f5acacc32a@AcuMS.aculab.com> From: Pavel Skripkin Message-ID: Date: Thu, 26 Aug 2021 23:03:04 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <6e864f9d133d4db3923190f5acacc32a@AcuMS.aculab.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 8/26/21 1:59 PM, David Laight wrote: > From: Pavel Skripkin >> Sent: 26 August 2021 11:55 >> >> On 8/26/21 1:22 PM, David Laight wrote: >> > From: Pavel Skripkin >> >> Sent: 26 August 2021 10:28 >> >> >> >> On 8/26/21 12:22 PM, Pavel Skripkin wrote: >> >> > On Thu, 26 Aug 2021 08:51:23 +0000 >> >> > David Laight wrote: >> > ... >> >> >> ... >> >> >> > -static u32 usb_read32(struct intf_hdl *pintfhdl, u32 addr) >> >> >> > +static int usb_read32(struct intf_hdl *pintfhdl, u32 addr, u32 >> >> >> > *data) { >> >> >> > u8 requesttype; >> >> >> > u16 wvalue; >> >> >> > u16 len; >> >> >> > - __le32 data; >> >> >> > + int res; >> >> >> > + __le32 tmp; >> >> >> > + >> >> >> > + if (WARN_ON(unlikely(!data))) >> >> >> > + return -EINVAL; >> >> >> > >> >> >> >> >> >> Kill the NULL check - it is a silly coding error. >> >> >> An OOPS is just as easy to debug. >> >> >> >> >> > >> >> > >> >> > I don't think that one single driver should kill the whole system. It's >> >> > 100% an error, but kernel can recover from it (for example disconnect >> >> > the driver, since it's broken). >> >> > >> >> > >> >> > AFIAK, Greg and Linus do not like BUG_ONs in recoverable state... >> >> > Correct me, if I am wrong >> >> > >> >> Oops, I thought about BUG_ON() instead of WARN_ON(), sorry for >> >> confusion. My point is "we should not let the box boom". >> > >> > >> > There is no point checking for NULL that just can't happen. >> > In this case all the callers will pass the address of a local. >> > There really is no point checking. >> > >> >> We not always read in local variable, there are few places, where we >> read into passed buffer. > > It is still a very local coding bug. > > David > Sure, but is defensive programming so bad? Greg, what your opinion about this NULL check? With regards, Pavel Skripkin