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SubjectRe: [PATCH] rtlwifi: rtl8192se firmware load can overflow target buffer
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@lwfinger.net>
>> Cc: Chaoming Li<chaoming_li@realsil.com.cn>
>> Cc: John W. Linville<linville@tuxdriver.com>
>> Cc: linux-wireless@vger.kernel.org
>> Cc: netdev@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Tim Gardner<tim.gardner@canonical.com>
>> ---
>> 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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