2018-08-24 02:57:49

by Ding Xiang

Subject: [PATCH] staging: greybus: Fix null pointer dereference

If fw is null then fw->size will trigger null pointer dereference

Signed-off-by: Ding Xiang <[email protected]>
---
drivers/staging/greybus/bootrom.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c
index e85ffae..3af28a0 100644
--- a/drivers/staging/greybus/bootrom.c
+++ b/drivers/staging/greybus/bootrom.c
@@ -297,7 +297,7 @@ static int gb_bootrom_get_firmware(struct gb_operation *op)

queue_work:
/* Refresh timeout */
- if (!ret && (offset + size == fw->size))
+ if (!ret && fw && (offset + size == fw->size))
next_request = NEXT_REQ_READY_TO_BOOT;
else
next_request = NEXT_REQ_GET_FIRMWARE;
--
1.8.3.1

2018-08-24 06:30:54

by Johan Hovold

Subject: Re: [PATCH] staging: greybus: Fix null pointer dereference

On Fri, Aug 24, 2018 at 12:07:11AM -0400, Ding Xiang wrote:
> If fw is null then fw->size will trigger null pointer dereference
>
> Signed-off-by: Ding Xiang <[email protected]>
> ---
> drivers/staging/greybus/bootrom.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c
> index e85ffae..3af28a0 100644
> --- a/drivers/staging/greybus/bootrom.c
> +++ b/drivers/staging/greybus/bootrom.c
> @@ -297,7 +297,7 @@ static int gb_bootrom_get_firmware(struct gb_operation *op)
>
> queue_work:
> /* Refresh timeout */
> - if (!ret && (offset + size == fw->size))
> + if (!ret && fw && (offset + size == fw->size))
> next_request = NEXT_REQ_READY_TO_BOOT;
> else
> next_request = NEXT_REQ_GET_FIRMWARE;

How could fw be NULL when ret is 0 here?

It may not be as obvious as one might have wished, but the current code
looks correct to me.

Johan

2018-08-24 10:10:20

by Ding Xiang

Subject: Re: [PATCH] staging: greybus: Fix null pointer dereference

Hi, Johan

    sorry, it's my fault.


On 8/24/2018 2:29 PM, Johan Hovold wrote:
> On Fri, Aug 24, 2018 at 12:07:11AM -0400, Ding Xiang wrote:
>> If fw is null then fw->size will trigger null pointer dereference
>>
>> Signed-off-by: Ding Xiang <[email protected]>
>> ---
>> drivers/staging/greybus/bootrom.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c
>> index e85ffae..3af28a0 100644
>> --- a/drivers/staging/greybus/bootrom.c
>> +++ b/drivers/staging/greybus/bootrom.c
>> @@ -297,7 +297,7 @@ static int gb_bootrom_get_firmware(struct gb_operation *op)
>>
>> queue_work:
>> /* Refresh timeout */
>> - if (!ret && (offset + size == fw->size))
>> + if (!ret && fw && (offset + size == fw->size))
>> next_request = NEXT_REQ_READY_TO_BOOT;
>> else
>> next_request = NEXT_REQ_GET_FIRMWARE;
> How could fw be NULL when ret is 0 here?
>
> It may not be as obvious as one might have wished, but the current code
> looks correct to me.
>
> Johan
>

2018-08-24 10:29:27

by Dan Carpenter

Subject: Re: [PATCH] staging: greybus: Fix null pointer dereference

On Fri, Aug 24, 2018 at 12:07:11AM -0400, Ding Xiang wrote:
> If fw is null then fw->size will trigger null pointer dereference
>
> Signed-off-by: Ding Xiang <[email protected]>
> ---
> drivers/staging/greybus/bootrom.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c
> index e85ffae..3af28a0 100644
> --- a/drivers/staging/greybus/bootrom.c
> +++ b/drivers/staging/greybus/bootrom.c
> @@ -297,7 +297,7 @@ static int gb_bootrom_get_firmware(struct gb_operation *op)
>
> queue_work:
> /* Refresh timeout */
> - if (!ret && (offset + size == fw->size))
> + if (!ret && fw && (offset + size == fw->size))

That is impossible. If "ret" is zero that implies "fw" is a valid
pointer.

regards,
dan carpenter