From: Pavel Skripkin <paskripkin@gmail.com>
To: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
Phillip Potter <phil@philpotter.co.uk>
Cc: Larry Finger <Larry.Finger@lwfinger.net>,
Greg KH <gregkh@linuxfoundation.org>,
Michael Straube <straube.linux@gmail.com>,
"open list:STAGING SUBSYSTEM" <linux-staging@lists.linux.dev>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32
Date: Tue, 24 Aug 2021 09:40:18 +0300 [thread overview]
Message-ID: <2355365e-d75e-8d1b-aad8-6979b70f33ec@gmail.com> (raw)
In-Reply-To: <2424268.2DCLMNk6Lg@localhost.localdomain>
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 <paskripkin@gmail.com> 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
next prev parent reply other threads:[~2021-08-24 6:40 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 17:07 [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-20 17:07 ` [PATCH RFC 1/3] staging: r8188eu: add proper rtw_read* error handling Pavel Skripkin
2021-08-20 21:50 ` Pavel Skripkin
2021-08-20 23:41 ` Phillip Potter
2021-08-21 5:55 ` Fabio M. De Francesco
2021-08-21 10:35 ` Pavel Skripkin
2021-08-21 12:11 ` Fabio M. De Francesco
2021-08-20 17:07 ` [PATCH RFC 2/3] staging: r8188eu: add error handling to ReadFuse Pavel Skripkin
2021-08-20 23:51 ` Phillip Potter
2021-08-21 3:59 ` Fabio M. De Francesco
2021-08-20 17:07 ` [PATCH RFC 3/3] staging: r8188eu: add error argument to read_macreg Pavel Skripkin
2021-08-20 23:18 ` Phillip Potter
2021-08-21 10:38 ` Pavel Skripkin
2021-08-20 23:12 ` [PATCH RFC 0/3] staging: r8188eu: avoid uninit value bugs Phillip Potter
2021-08-21 10:42 ` Pavel Skripkin
2021-08-22 9:53 ` Fabio M. De Francesco
2021-08-22 10:09 ` Pavel Skripkin
2021-08-22 10:59 ` Fabio M. De Francesco
2021-08-22 11:34 ` Fabio M. De Francesco
2021-08-22 12:10 ` Pavel Skripkin
2021-08-22 12:39 ` Greg KH
2021-08-22 12:50 ` Pavel Skripkin
2021-08-22 13:06 ` Greg KH
2021-08-22 13:21 ` Fabio M. De Francesco
2021-08-22 13:30 ` Greg KH
2021-08-22 13:31 ` Pavel Skripkin
2021-08-22 14:35 ` [PATCH RFC v2 0/6] " Pavel Skripkin
2021-08-22 14:35 ` [PATCH RFC v2 1/6] staging: r8188eu: remove {read,write}_macreg Pavel Skripkin
2021-08-22 14:35 ` [PATCH RFC v2 2/6] staging: r8188eu: add helper macro for printing registers Pavel Skripkin
2021-08-22 14:35 ` [PATCH RFC v2 3/6] staging: r8188eu: add error handling of rtw_read8 Pavel Skripkin
2021-08-22 14:35 ` [PATCH RFC v2 4/6] staging: r8188eu: add error handling of rtw_read16 Pavel Skripkin
2021-08-22 14:36 ` [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Pavel Skripkin
2021-08-23 23:33 ` Phillip Potter
2021-08-24 0:10 ` Fabio M. De Francesco
2021-08-24 6:40 ` Pavel Skripkin [this message]
2021-08-24 8:38 ` Fabio M. De Francesco
2021-08-24 8:47 ` Pavel Skripkin
2021-08-24 8:53 ` Pavel Skripkin
2021-08-24 9:46 ` Fabio M. De Francesco
2021-08-24 22:10 ` Phillip Potter
2021-08-24 22:07 ` Phillip Potter
2021-08-24 6:53 ` Pavel Skripkin
2021-08-24 7:25 ` [PATCH v3 0/6] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-24 7:27 ` [PATCH v3 1/6] staging: r8188eu: remove {read,write}_macreg Pavel Skripkin
2021-08-26 10:39 ` Greg KH
2021-08-26 10:40 ` Greg KH
2021-08-24 7:27 ` [PATCH v3 2/6] staging: r8188eu: add helper macro for printing registers Pavel Skripkin
2021-08-26 10:37 ` Greg KH
2021-08-24 7:27 ` [PATCH v3 3/6] staging: r8188eu: add error handling of rtw_read8 Pavel Skripkin
2021-08-25 12:05 ` kernel test robot
2021-08-25 12:17 ` Pavel Skripkin
2021-08-25 12:51 ` Dan Carpenter
2021-08-25 13:02 ` Pavel Skripkin
2021-08-25 13:34 ` Dan Carpenter
2021-08-25 13:44 ` Pavel Skripkin
2021-08-25 17:11 ` Nick Desaulniers
2021-08-26 11:08 ` Dan Carpenter
2021-08-25 23:45 ` Fabio M. De Francesco
2021-08-26 5:13 ` Pavel Skripkin
2021-08-26 8:21 ` David Laight
2021-08-26 8:27 ` Pavel Skripkin
2021-08-26 10:19 ` David Laight
2021-08-26 11:21 ` Dan Carpenter
2021-08-27 8:14 ` David Laight
2021-08-27 8:22 ` Pavel Skripkin
2021-08-27 9:07 ` Dan Carpenter
2021-08-27 9:16 ` Pavel Skripkin
2021-08-27 9:23 ` Dan Carpenter
2021-08-30 11:21 ` kernel test robot
2021-08-24 7:27 ` [PATCH v3 4/6] staging: r8188eu: add error handling of rtw_read16 Pavel Skripkin
2021-08-25 4:35 ` Fabio M. De Francesco
2021-08-25 8:22 ` Pavel Skripkin
2021-08-25 9:48 ` Fabio M. De Francesco
2021-08-25 9:55 ` Pavel Skripkin
2021-08-25 10:06 ` Dan Carpenter
2021-08-25 10:13 ` Pavel Skripkin
2021-08-25 10:38 ` Dan Carpenter
2021-08-25 10:41 ` Pavel Skripkin
2021-08-25 11:06 ` Fabio M. De Francesco
2021-08-25 11:11 ` Fabio M. De Francesco
2021-08-25 11:31 ` Dan Carpenter
2021-08-25 12:11 ` Fabio M. De Francesco
2021-08-25 10:51 ` Fabio M. De Francesco
2021-08-26 10:50 ` Greg KH
2021-08-26 10:58 ` Pavel Skripkin
2021-08-24 7:27 ` [PATCH v3 5/6] staging: r8188eu: add error handling of rtw_read32 Pavel Skripkin
2021-08-25 4:40 ` Fabio M. De Francesco
2021-08-26 8:51 ` David Laight
2021-08-26 9:22 ` Pavel Skripkin
2021-08-26 9:27 ` Pavel Skripkin
2021-08-26 10:22 ` David Laight
2021-08-26 10:55 ` Pavel Skripkin
2021-08-26 10:59 ` David Laight
2021-08-26 20:03 ` Pavel Skripkin
2021-08-27 7:12 ` gregkh
2021-08-27 7:16 ` Pavel Skripkin
2021-08-24 7:27 ` [PATCH v3 6/6] staging: r8188eu: make ReadEFuse return an int Pavel Skripkin
2021-08-25 10:13 ` [PATCH v3 0/6] staging: r8188eu: avoid uninit value bugs Fabio M. De Francesco
2021-08-27 7:49 ` Kari Argillander
2021-08-27 7:52 ` Pavel Skripkin
2021-08-24 6:58 ` [PATCH RFC v2 5/6] staging: r8188eu: add error handling of rtw_read32 Dan Carpenter
2021-08-24 7:01 ` Pavel Skripkin
2021-08-24 15:07 ` Fabio M. De Francesco
2021-08-22 14:36 ` [PATCH RFC v2 6/6] staging: r8188eu: make ReadEFuse return an int Pavel Skripkin
2021-08-22 15:30 ` [PATCH RFC v2 0/6] staging: r8188eu: avoid uninit value bugs Pavel Skripkin
2021-08-22 16:05 ` Michael Straube
2021-08-22 16:26 ` Pavel Skripkin
2021-08-22 23:52 ` Phillip Potter
2021-08-22 17:36 ` Fabio M. De Francesco
2021-08-22 17:38 ` Pavel Skripkin
2021-08-22 20:06 ` Fabio M. De Francesco
2021-08-22 20:19 ` Pavel Skripkin
2021-08-23 0:12 ` Phillip Potter
2021-08-23 6:38 ` Pavel Skripkin
2021-08-23 6:44 ` Pavel Skripkin
2021-08-22 16:03 ` [PATCH RFC 0/3] " Fabio M. De Francesco
2021-08-22 16:15 ` Pavel Skripkin
2021-08-22 15:04 ` Phillip Potter
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