linux-kernel - Re: staging: r8188eu: struct rt_firmware

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Date:   Wed, 13 Apr 2022 16:12:07 -0500
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Michael Straube <straube.linux@...il.com>
Cc:     Phillip Potter <phil@...lpotter.co.uk>,
        Greg KH <gregkh@...uxfoundation.org>,
        "open list:STAGING SUBSYSTEM" <linux-staging@...ts.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: staging: r8188eu: struct rt_firmware_header issues

On 4/13/22 14:42, Michael Straube wrote:
> On 4/13/22 18:27, Michael Straube wrote:
>> Hi all,
>>
>> I think the rt_firmware_hdr structure in rtw_fw.c has some issues.
>>
>>
>> struct rt_firmware_hdr {
>>      /*  8-byte alinment required */
>>      /*  LONG WORD 0 ---- */
>>      __le16        Signature;    /* 92C0: test chip; 92C,
>>                       * 88C0: test chip; 88C1: MP A-cut;
>>                       * 92C1: MP A-cut */
>>      u8        Category;    /*  AP/NIC and USB/PCI */
>>      u8        Function;    /*  Reserved for different FW function
>>                       *  indcation, for further use when
>>                       *  driver needs to download different
>>                       *  FW for different conditions */
>>      __le16        Version;    /*  FW Version */
>>      u8        Subversion;    /*  FW Subversion, default 0x00 */
>>      u16        Rsvd1;
>>
>>      /*  LONG WORD 1 ---- */
>>      u8        Month;    /*  Release time Month field */
>>      u8        Date;    /*  Release time Date field */
>>      u8        Hour;    /*  Release time Hour field */
>>      u8        Minute;    /*  Release time Minute field */
>>      __le16        RamCodeSize;    /*  The size of RAM code */
>>      u8        Foundry;
>>      u8        Rsvd2;
>>
>>      /*  LONG WORD 2 ---- */
>>      __le32        SvnIdx;    /*  The SVN entry index */
>>      u32        Rsvd3;
>>
>>      /*  LONG WORD 3 ---- */
>>      u32        Rsvd4;
>>      u32        Rsvd5;
>> };
>>
>>
>> Then we have in rtl8188e_firmware_download():
>>
>>
>>      fwhdr = (struct rt_firmware_hdr *)dvobj->firmware.data;
>>
>>      <snip>
>>
>>      if (IS_FW_HEADER_EXIST(fwhdr)) {
>>          /*  Shift 32 bytes for FW header */
>>          fw_data = fw_data + 32;
>>          fw_size = fw_size - 32;
>>      }
>>
>> We add/sub 32 bytes but the size of struct rt_firmware_hdr is actually
>> 33 bytes. I noticed this when I wanted to replace:
>>
>>          fw_data = fw_data + 32;
>>          fw_size = fw_size - 32;
>>
>> with:
>>          fw_data = fw_data + sizeof(struct rt_firmware_hdr);
>>          fw_size = fw_size - sizeof(struct rt_firmware_hdr);;
>>
>> To me it looks add/sub 32 is correct here but the struct is
>> wrong. I don't know if the firmware for this driver is so much different
>> from firmware for the drivers in drivers/net/wireless/realtek/rtlwifi.
>> They use a struct of size 32.
>>
>> Also, souldn't the u16 and u32 variables in the struct be __le16 and
>> __le32 ?
>>
>> I wonder if we can just use the rtlwifi_firmware_header structure from
>> drivers/net/wireless/realtek/rtlwifi/wifi.h ?
>>
>> Comments from people with better knowledge appreciated. :)
>>
>> regards,
>> Michael
>>
>>
> 
> Ok, I figured it out by looking at the hexdumps of firmware files. The
> field Rsvd1 should be u8 instead of u16. I'll prepare a patch for this.

I agree. I had prepared an analysis, but did not get it mailed before I got this 
one.

Larry