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

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Message-ID: <86a66ea4-45e3-cfa2-9130-f698ae212bfd@gmail.com>
Date:   Wed, 13 Apr 2022 21:42:28 +0200
From:   Michael Straube <straube.linux@...il.com>
To:     Larry Finger <Larry.Finger@...inger.net>
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 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.

regards,
Michael