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Date:   Tue, 11 May 2021 10:47:50 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Kees Cook <keescook@...omium.org>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] media: siano: Fix multiple out-of-bounds warnings
 in smscore_load_firmware_family2()


By the way, we are about to be able to globally enable -Warray-bounds and,
these are the last out-of-bounds warnings in linux-next.

Thanks
--
Gustavo

On 5/11/21 10:18, Gustavo A. R. Silva wrote:
> Hi all,
> 
> Friendly ping (second one): who can take this, please?
> 
> Thanks
> --
> Gustavo
> 
> On 3/26/21 11:30, Gustavo A. R. Silva wrote:
>> Hi all,
>>
>> Friendly ping: who can take this, please?
>>
>> Thanks
>> --
>> Gustavo
>>
>> On 3/10/21 20:19, Gustavo A. R. Silva wrote:
>>> Rename struct sms_msg_data4 to sms_msg_data5 and increase the size of
>>> its msg_data array from 4 to 5 elements. Notice that at some point
>>> the 5th element of msg_data is being accessed in function
>>> smscore_load_firmware_family2():
>>>
>>> 1006                 trigger_msg->msg_data[4] = 4; /* Task ID */
>>>
>>> Also, there is no need for the object _trigger_msg_ of type struct
>>> sms_msg_data *, when _msg_ can be used, directly. Notice that msg_data
>>> in struct sms_msg_data is a one-element array, which causes multiple
>>> out-of-bounds warnings when accessing beyond its first element
>>> in function smscore_load_firmware_family2():
>>>
>>>  992                 struct sms_msg_data *trigger_msg =                                                  
>>>  993                         (struct sms_msg_data *) msg;                                                
>>>  994                                                                                                     
>>>  995                 pr_debug("sending MSG_SMS_SWDOWNLOAD_TRIGGER_REQ\n");                               
>>>  996                 SMS_INIT_MSG(&msg->x_msg_header,                                                    
>>>  997                                 MSG_SMS_SWDOWNLOAD_TRIGGER_REQ,                                     
>>>  998                                 sizeof(struct sms_msg_hdr) +                                        
>>>  999                                 sizeof(u32) * 5);                                                   
>>> 1000                                                                                                     
>>> 1001                 trigger_msg->msg_data[0] = firmware->start_address;                                 
>>> 1002                                         /* Entry point */                                           
>>> 1003                 trigger_msg->msg_data[1] = 6; /* Priority */                                        
>>> 1004                 trigger_msg->msg_data[2] = 0x200; /* Stack size */                                  
>>> 1005                 trigger_msg->msg_data[3] = 0; /* Parameter */                                       
>>> 1006                 trigger_msg->msg_data[4] = 4; /* Task ID */ 
>>>
>>> even when enough dynamic memory is allocated for _msg_:
>>>
>>>  929         /* PAGE_SIZE buffer shall be enough and dma aligned */
>>>  930         msg = kmalloc(PAGE_SIZE, GFP_KERNEL | coredev->gfp_buf_flags);
>>>
>>> but as _msg_ is casted to (struct sms_msg_data *):
>>>
>>>  992                 struct sms_msg_data *trigger_msg =
>>>  993                         (struct sms_msg_data *) msg;
>>>
>>> the out-of-bounds warnings are actually valid and should be addressed.
>>>
>>> Fix this by declaring object _msg_ of type struct sms_msg_data5 *,
>>> which contains a 5-elements array, instead of just 4. And use
>>> _msg_ directly, instead of creating object trigger_msg.
>>>
>>> This helps with the ongoing efforts to enable -Warray-bounds by fixing
>>> the following warnings:
>>>
>>>   CC [M]  drivers/media/common/siano/smscoreapi.o
>>> drivers/media/common/siano/smscoreapi.c: In function ‘smscore_load_firmware_family2’:
>>> drivers/media/common/siano/smscoreapi.c:1003:24: warning: array subscript 1 is above array bounds of ‘u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds]
>>>  1003 |   trigger_msg->msg_data[1] = 6; /* Priority */
>>>       |   ~~~~~~~~~~~~~~~~~~~~~^~~
>>> In file included from drivers/media/common/siano/smscoreapi.c:12:
>>> drivers/media/common/siano/smscoreapi.h:619:6: note: while referencing ‘msg_data’
>>>   619 |  u32 msg_data[1];
>>>       |      ^~~~~~~~
>>> drivers/media/common/siano/smscoreapi.c:1004:24: warning: array subscript 2 is above array bounds of ‘u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds]
>>>  1004 |   trigger_msg->msg_data[2] = 0x200; /* Stack size */
>>>       |   ~~~~~~~~~~~~~~~~~~~~~^~~
>>> In file included from drivers/media/common/siano/smscoreapi.c:12:
>>> drivers/media/common/siano/smscoreapi.h:619:6: note: while referencing ‘msg_data’
>>>   619 |  u32 msg_data[1];
>>>       |      ^~~~~~~~
>>> drivers/media/common/siano/smscoreapi.c:1005:24: warning: array subscript 3 is above array bounds of ‘u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds]
>>>  1005 |   trigger_msg->msg_data[3] = 0; /* Parameter */
>>>       |   ~~~~~~~~~~~~~~~~~~~~~^~~
>>> In file included from drivers/media/common/siano/smscoreapi.c:12:
>>> drivers/media/common/siano/smscoreapi.h:619:6: note: while referencing ‘msg_data’
>>>   619 |  u32 msg_data[1];
>>>       |      ^~~~~~~~
>>> drivers/media/common/siano/smscoreapi.c:1006:24: warning: array subscript 4 is above array bounds of ‘u32[1]’ {aka ‘unsigned int[1]’} [-Warray-bounds]
>>>  1006 |   trigger_msg->msg_data[4] = 4; /* Task ID */
>>>       |   ~~~~~~~~~~~~~~~~~~~~~^~~
>>> In file included from drivers/media/common/siano/smscoreapi.c:12:
>>> drivers/media/common/siano/smscoreapi.h:619:6: note: while referencing ‘msg_data’
>>>   619 |  u32 msg_data[1];
>>>       |      ^~~~~~~~
>>>
>>> Fixes: 018b0c6f8acb ("[media] siano: make load firmware logic to work with newer firmwares")
>>> Co-developed-by: Kees Cook <keescook@...omium.org>
>>> Signed-off-by: Kees Cook <keescook@...omium.org>
>>> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
>>> ---
>>>  drivers/media/common/siano/smscoreapi.c | 22 +++++++++-------------
>>>  drivers/media/common/siano/smscoreapi.h |  4 ++--
>>>  2 files changed, 11 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/drivers/media/common/siano/smscoreapi.c b/drivers/media/common/siano/smscoreapi.c
>>> index 410cc3ac6f94..bceaf91faa15 100644
>>> --- a/drivers/media/common/siano/smscoreapi.c
>>> +++ b/drivers/media/common/siano/smscoreapi.c
>>> @@ -908,7 +908,7 @@ static int smscore_load_firmware_family2(struct smscore_device_t *coredev,
>>>  					 void *buffer, size_t size)
>>>  {
>>>  	struct sms_firmware *firmware = (struct sms_firmware *) buffer;
>>> -	struct sms_msg_data4 *msg;
>>> +	struct sms_msg_data5 *msg;
>>>  	u32 mem_address,  calc_checksum = 0;
>>>  	u32 i, *ptr;
>>>  	u8 *payload = firmware->payload;
>>> @@ -989,24 +989,20 @@ static int smscore_load_firmware_family2(struct smscore_device_t *coredev,
>>>  		goto exit_fw_download;
>>>  
>>>  	if (coredev->mode == DEVICE_MODE_NONE) {
>>> -		struct sms_msg_data *trigger_msg =
>>> -			(struct sms_msg_data *) msg;
>>> -
>>>  		pr_debug("sending MSG_SMS_SWDOWNLOAD_TRIGGER_REQ\n");
>>>  		SMS_INIT_MSG(&msg->x_msg_header,
>>>  				MSG_SMS_SWDOWNLOAD_TRIGGER_REQ,
>>> -				sizeof(struct sms_msg_hdr) +
>>> -				sizeof(u32) * 5);
>>> +				sizeof(*msg));
>>>  
>>> -		trigger_msg->msg_data[0] = firmware->start_address;
>>> +		msg->msg_data[0] = firmware->start_address;
>>>  					/* Entry point */
>>> -		trigger_msg->msg_data[1] = 6; /* Priority */
>>> -		trigger_msg->msg_data[2] = 0x200; /* Stack size */
>>> -		trigger_msg->msg_data[3] = 0; /* Parameter */
>>> -		trigger_msg->msg_data[4] = 4; /* Task ID */
>>> +		msg->msg_data[1] = 6; /* Priority */
>>> +		msg->msg_data[2] = 0x200; /* Stack size */
>>> +		msg->msg_data[3] = 0; /* Parameter */
>>> +		msg->msg_data[4] = 4; /* Task ID */
>>>  
>>> -		rc = smscore_sendrequest_and_wait(coredev, trigger_msg,
>>> -					trigger_msg->x_msg_header.msg_length,
>>> +		rc = smscore_sendrequest_and_wait(coredev, msg,
>>> +					msg->x_msg_header.msg_length,
>>>  					&coredev->trigger_done);
>>>  	} else {
>>>  		SMS_INIT_MSG(&msg->x_msg_header, MSG_SW_RELOAD_EXEC_REQ,
>>> diff --git a/drivers/media/common/siano/smscoreapi.h b/drivers/media/common/siano/smscoreapi.h
>>> index 4a6b9f4c44ac..f8789ee0d554 100644
>>> --- a/drivers/media/common/siano/smscoreapi.h
>>> +++ b/drivers/media/common/siano/smscoreapi.h
>>> @@ -624,9 +624,9 @@ struct sms_msg_data2 {
>>>  	u32 msg_data[2];
>>>  };
>>>  
>>> -struct sms_msg_data4 {
>>> +struct sms_msg_data5 {
>>>  	struct sms_msg_hdr x_msg_header;
>>> -	u32 msg_data[4];
>>> +	u32 msg_data[5];
>>>  };
>>>  
>>>  struct sms_data_download {
>>>

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