From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f43.google.com (mail-ej1-f43.google.com [209.85.218.43]) (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 2EFE929CA for ; Tue, 24 Aug 2021 00:10:42 +0000 (UTC) Received: by mail-ej1-f43.google.com with SMTP id w5so40564628ejq.2 for ; Mon, 23 Aug 2021 17:10:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=FFa/vNXbOTkZVECzFyo1BP3x0iFIJhbAlOvPMoA4Yo4=; b=bm2bQu1aHZ9J8cmciQhZPFBuntv/uZy6KS3dfLJAqaaUHSfjLev+ubv/Aj6xbD7Dwu gWVQ6t8c+vG9qgCm1a33LkhOUWg52KmQzIAqoQJOaySbfFhfmLZdbpv9N9KM5vIMG+8z X9/Ed3J2WS4CiJUpNzl0blpe4lxwyj4W+H+dE7L08KBJlYFRAEk4mCpentH/GwBzAv0X iJ3karqOibXrgSMNNO8DLbIhPYJT+xcDX/Z5fjA8d+1zWN2OMXxG8MJvcBl0hPXMJpwZ 0xL7XxZOOnlawvbXiJ3N4vaTaG4E9MnHaBOHoSq5kc70G3uUBQkVRr+5KXIJhZ9IJg4P vTYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=FFa/vNXbOTkZVECzFyo1BP3x0iFIJhbAlOvPMoA4Yo4=; b=BQ1I3yqsdnZNp6hWwgULIZhE04dwAlOYyawUxsG1exMu/Kpy6au9NvxV39jZxWjTxa 6t8FG1mKLlPhYPEEmJphzWmwKcE4uBNJqr3/Pftq59UOcccELg0EQyyiGIkTKCVzLajz iHLYbMi7qT+ryXcfuKFpDlx9eXTEop7C3i7A15uUuIpF+S5ZZJNXyxMXKcPsvOGC9vJX NfcQFHmw8O+45pU1EWZoTuHmIR1Cl4h/P+mzBBL20SjNf8h0tl9MPIsVHtcz94JrVu3h eRemR5DbZp8tnlsyEi12LcvX9KpxlR0ucN+/I9j2RJrz32iSmsIjTvTMOrEatNxUVhA7 dJrw== X-Gm-Message-State: AOAM532Jo2I4hqcA9ptaFP7PHifeeqh4rRpzeyb6HLUp2x1zepBTvuge I56Z+eivqqpy0qfhaPaclZQ= X-Google-Smtp-Source: ABdhPJzPbz9pHA31WemzzpNGNV/666FPgTsPXhwuhMdh35F/9FiJdWh1JuiiV/rsJSc24hpsXRGBQg== X-Received: by 2002:a17:906:5497:: with SMTP id r23mr1262301ejo.302.1629763840571; Mon, 23 Aug 2021 17:10:40 -0700 (PDT) Received: from localhost.localdomain (host-79-22-100-164.retail.telecomitalia.it. [79.22.100.164]) by smtp.gmail.com with ESMTPSA id m19sm10042670edd.38.2021.08.23.17.10.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Aug 2021 17:10:40 -0700 (PDT) From: "Fabio M. De Francesco" To: Pavel Skripkin , Phillip Potter Cc: Larry Finger , Greg KH , Michael Straube , "open list:STAGING SUBSYSTEM" , Linux Kernel Mailing List Subject: Re: [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Date: Tue, 24 Aug 2021 02:10:37 +0200 Message-ID: <2424268.2DCLMNk6Lg@localhost.localdomain> In-Reply-To: References: <9004eb2972780455db4cba9694244a2c572abba8.1629642658.git.paskripkin@gmail.com> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="UTF-8" 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*(). Regards, Fabio > > Regards, > Phil >