From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lj1-f182.google.com (mail-lj1-f182.google.com [209.85.208.182]) (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 34B293FC1 for ; Tue, 24 Aug 2021 06:40:22 +0000 (UTC) Received: by mail-lj1-f182.google.com with SMTP id d16so35741166ljq.4 for ; Mon, 23 Aug 2021 23:40:22 -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=ZQZLq6uBAFATkrorgtZ8B76K/WqmPO2TDZRH4lVEcfg=; b=GAFy051dod8TdxyPeZ2ozDpIXNG4JHdRpaYe21tgKtgP81lIWdrnDfyuYJh2gxivIZ 0yQK6+2AJReiFvjkdTr+DZN2j7gt60ypRvFi0IOCyW3BAwurjmQa8QrenQtSyZfch4x1 rRJmXioleBwi123kNbHwIyRhDdjx62rmKNRryy056g1CSvwBp/2tSG/8KVoYDDjTt48A I1UlDmYR1s3JXbMlp4rXp0VBfTviErB3vr3+RB2dMq+h7ft4/ZHvR/5VuzH8QmFuDi19 e6Qo0+FD7Zt5O6PkebT5dH/n5gBidY27Q42mJUR6mMPuEnQ7Lwn/P4OAUdiMyOa3dckx qLqg== 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=ZQZLq6uBAFATkrorgtZ8B76K/WqmPO2TDZRH4lVEcfg=; b=YV9xmkQyQbsA0vzmU8c4ZO9QUNY2tXMQaL6w725Pm3BHrmqzLSomSOm8Qamd1l6KLl tLak9u3b/AlL3WV6tPVPW+SWGWeRGxh+FLE50IktVeAQz0a/nsAZrq2hwGZ2qU+OnACn DK3Fc9rAA1PER9x94+DesLuCMKLcsSjEKBbUZrEiTZGE7uaHOm8cOuWLeUNN5uvGfaSU OK29FrtX6hLR7GGaJL1gnOBfNAjU3rqPLlMHygPEsuIHr9MtNj/AbBB1cLrh3OSjmRB3 ulWX01TdzQhqF8VWSgoPG2DhDa/l31XmyWxmK6QiMVatAdYJM8yq5vYSXIE/wcmv30G8 NQMg== X-Gm-Message-State: AOAM530dUg6liYEoU6Ej6hgh3zcQXrO+agSOncyWZljo6wSXPK9OXmJr IIAiP5jTaifD5q96Iy7Jg/Q= X-Google-Smtp-Source: ABdhPJyhmESxjZeg7EX6mXKhJdCMqFbUzDRd5LYK5u7dkdhLmLykXH3rqjUZ9qSgGcC9R/7T1B/7zA== X-Received: by 2002:a2e:9010:: with SMTP id h16mr30233686ljg.484.1629787220220; Mon, 23 Aug 2021 23:40:20 -0700 (PDT) Received: from [192.168.1.11] ([46.235.66.127]) by smtp.gmail.com with ESMTPSA id w8sm1662598lfn.37.2021.08.23.23.40.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Aug 2021 23:40:19 -0700 (PDT) Subject: Re: [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 To: "Fabio M. De Francesco" , Phillip Potter Cc: Larry Finger , Greg KH , Michael Straube , "open list:STAGING SUBSYSTEM" , Linux Kernel Mailing List References: <9004eb2972780455db4cba9694244a2c572abba8.1629642658.git.paskripkin@gmail.com> <2424268.2DCLMNk6Lg@localhost.localdomain> From: Pavel Skripkin Message-ID: <2355365e-d75e-8d1b-aad8-6979b70f33ec@gmail.com> Date: Tue, 24 Aug 2021 09:40:18 +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: <2424268.2DCLMNk6Lg@localhost.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 8/24/21 3:10 AM, Fabio M. De Francesco wrote: > On Tuesday, August 24, 2021 1:33:46 AM CEST Phillip Potter wrote: >> On Sun, 22 Aug 2021 at 15:36, Pavel Skripkin 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; >> > >> > requesttype = 0x01;/* read_in */ >> > >> > wvalue = (u16)(addr & 0x0000ffff); >> > len = 4; >> > >> > - usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype); >> > + res = usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype); >> > + if (res < 0) { >> > + dev_err(dvobj_to_dev(pintfhdl->pintf_dev), "Failed to read 32 bytes: %d\n", res); >> > + } else { >> > + /* Noone cares about positive return value */ >> > + *data = le32_to_cpu(tmp); >> > + res = 0; >> > + } >> > >> > - return le32_to_cpu(data); >> > + return res; >> > } >> >> Dear Pavel, >> >> OK, found the issue with decoded stack trace after reviewing this >> usb_read32 function. Your line: >> res = usbctrl_vendorreq(pintfhdl, wvalue, &data, len, requesttype); >> >> should read: >> res = usbctrl_vendorreq(pintfhdl, wvalue, &tmp, len, requesttype); > > Dear Philip, > > No, it should read: > > res = usbctrl_vendorreq(pintfhdl, wvalue, data, len, requesttype); > > I suspect that Pavel didn't notice he was reusing a line of the old code > wth no due changes. > >> With this change, the driver runs fine with no crashes/oopses. I will >> explain the issue but you can probably see already, so I hope I'm not >> coming across as patronising, just trying to be helpful :-) >> >> Essentially, you are taking the address of the data function parameter >> on this line with &data, a pointer to u32, which is giving you a >> pointer to a pointer to u32 (u32 **) for this function parameter >> variable. When passed to usbctrl_vendorreq, it is being passed to >> memcpy inside this function as a void *, meaning that memcpy >> subsequently overwrites the value of the memory address inside data to >> point to a different location, which is problem when it is later >> deferenced at: >> *data = le32_to_cpu(tmp); >> causing the OOPS >> >> Also, as written, you can probably see that tmp is uninitialised. This >> looks like a typo, so guessing this wasn't your intention. Anyhow, >> with that small change, usbctrl_vendorreq reads into tmp, which is >> then passed to le32_to_cpu whose return value is stored via the >> deferenced data ptr (which now has its original address within and not >> inadvertently modified). Hope this helps, and I'd be happy to Ack the >> series if you want to resend this patch. Many thanks. > > I think that another typo is having 'tmp', because that variable is unnecessary > and "*data = le32_to_cpu(tmp);" is wrong too. > > Now I also see that also usb_read16() is wrong, while usb_read8() (the one that > I had read yesterday) is the only correct function of the three usb_read*(). > Hi, guys! Sorry for breaking your system, Phillip. This code was part of "last minute" changes and yes, it's broken :) I get what Phillip said, because I _should_ read into tmp variable instead of directly to data, but I don't get Fabio's idea, sorry. Data from chip comes in little-endian, so we _should_ convert it to cpu's endian. Temp variable is needed to make smatch and all other static anylis tools happy about this code. If I am missing something, please, let me know :) v3 is on the way... With regards, Pavel Skripkin