Re: [PATCH] rtlwifi: rtl8192se firmware load can overflow targetbuffer

[Larry Finger]

On 02/08/2012 03:45 PM, Ben Hutchings wrote:
> On Wed, 2012-02-08 at 14:08 -0700, Tim Gardner wrote:
> > The firmware file size check does not use the
> > correct limit.
> >
> > Cc: Larry Finger<Larry.Finger@xxxxxxxxxxxx>
> > Cc: Chaoming Li<chaoming_li@xxxxxxxxxxxxxx>
> > Cc: John W. Linville<linville@xxxxxxxxxxxxx>
> > Cc: linux-wireless@xxxxxxxxxxxxxxx
> > Cc: netdev@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Signed-off-by: Tim Gardner<tim.gardner@xxxxxxxxxxxxx>
> > ---
> >   drivers/net/wireless/rtlwifi/rtl8192se/fw.h |    3 ++-
> >   drivers/net/wireless/rtlwifi/rtl8192se/sw.c |    2 +-
> >   2 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/wireless/rtlwifi/rtl8192se/fw.h b/drivers/net/wireless/rtlwifi/rtl8192se/fw.h
> > index babe85d..5c377fc 100644
> > --- a/drivers/net/wireless/rtlwifi/rtl8192se/fw.h
> > +++ b/drivers/net/wireless/rtlwifi/rtl8192se/fw.h
> > @@ -30,6 +30,7 @@
> >   #define __REALTEK_FIRMWARE92S_H__
> >
> >   #define RTL8190_MAX_FIRMWARE_CODE_SIZE		64000
> > +#define RTL8190_MAX_RAW_FIRMWARE_CODE_SIZE	164000

The current size of the firmware is 88,856, thus the value of 
RTL8190_MAX_RAW_FIRMWARE_CODE_SIZE should be set to 90,000 to allow for some 
growth in the size of the firmware. Using 164,000 wastes a lot of space.

> >   #define RTL8190_CPU_START_OFFSET		0x80
> >   /* Firmware Local buffer size. 64k */
> >   #define	MAX_FIRMWARE_CODE_SIZE			0xFF00
> > @@ -217,7 +218,7 @@ struct rt_firmware {
> >   	u8 fw_emem[RTL8190_MAX_FIRMWARE_CODE_SIZE];
> >   	u32 fw_imem_len;
> >   	u32 fw_emem_len;
> > -	u8 sz_fw_tmpbuffer[164000];
> > +	u8 sz_fw_tmpbuffer[RTL8190_MAX_RAW_FIRMWARE_CODE_SIZE];
> >   	u32 sz_fw_tmpbufferlen;
> >   	u16 cmdpacket_fragthresold;
> >   };
> > diff --git a/drivers/net/wireless/rtlwifi/rtl8192se/sw.c b/drivers/net/wireless/rtlwifi/rtl8192se/sw.c
> > index ca38dd9..155da0a 100644
> > --- a/drivers/net/wireless/rtlwifi/rtl8192se/sw.c
> > +++ b/drivers/net/wireless/rtlwifi/rtl8192se/sw.c
> > @@ -105,7 +105,7 @@ static void rtl92se_fw_cb(const struct firmware *firmware, void *context)
> >   		rtlpriv->max_fw_size = 0;
> >   		return;
> >   	}
> > -	if (firmware->size>  rtlpriv->max_fw_size) {
> > +	if (firmware->size>= RTL8190_MAX_RAW_FIRMWARE_CODE_SIZE) {

Do not change this one. rtlpriv->max_fw_size has been set to sizeof(struct 
rt_firmware), which is correct.

> This appears to reject a firmware blob which is exactly the maximum
> size, which looks wrong.  Also doesn't this make the max_fw_size field
> redundant?

I commented on this one earlier, but to reiterate - max_fw_size is not redundant.

Larry
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