[PATCH] mtip32xx: use formatting capability of kthread_create_on_node

[PATCH] mtip32xx: use formatting capability of kthread_create_on_node

[Rasmus Villemoes]

kthread_create_on_node takes format+args, so there's no need to do the
pretty-printing in advance. Moreover, "mtip_svc_thd_99" (including its
'\0') only just fits in 16 bytes, so if index could ever go above 99
we'd have a stack buffer overflow.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/block/mtip32xx/mtip32xx.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index a28a562f7b7f..3457ac8c03e2 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -3810,7 +3810,6 @@ static int mtip_block_initialize(struct driver_data *dd)
 	sector_t capacity;
 	unsigned int index = 0;
 	struct kobject *kobj;
-	unsigned char thd_name[16];
 
 	if (dd->disk)
 		goto skip_create_disk; /* hw init done, before rebuild */
@@ -3958,10 +3957,9 @@ skip_create_disk:
 	}
 
 start_service_thread:
-	sprintf(thd_name, "mtip_svc_thd_%02d", index);
 	dd->mtip_svc_handler = kthread_create_on_node(mtip_service_thread,
-						dd, dd->numa_node, "%s",
-						thd_name);
+						dd, dd->numa_node,
+						"mtip_svc_thd_%02d", index);
 
 	if (IS_ERR(dd->mtip_svc_handler)) {
 		dev_err(&dd->pdev->dev, "service thread failed to start\n");
-- 
2.6.1

Re: [PATCH] mtip32xx: use formatting capability of kthread_create_on_node

[Jeff Moyer]

Rasmus Villemoes <linux@rasmusvillemoes.dk> writes:

> kthread_create_on_node takes format+args, so there's no need to do the
> pretty-printing in advance. Moreover, "mtip_svc_thd_99" (including its
> '\0') only just fits in 16 bytes, so if index could ever go above 99
> we'd have a stack buffer overflow.

I don't know of any systems with enough pci slots to expand index
beyond 99.  However, the patch looks like a good cleanup to me.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>

> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  drivers/block/mtip32xx/mtip32xx.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
> index a28a562f7b7f..3457ac8c03e2 100644
> --- a/drivers/block/mtip32xx/mtip32xx.c
> +++ b/drivers/block/mtip32xx/mtip32xx.c
> @@ -3810,7 +3810,6 @@ static int mtip_block_initialize(struct driver_data *dd)
>  	sector_t capacity;
>  	unsigned int index = 0;
>  	struct kobject *kobj;
> -	unsigned char thd_name[16];
>  
>  	if (dd->disk)
>  		goto skip_create_disk; /* hw init done, before rebuild */
> @@ -3958,10 +3957,9 @@ skip_create_disk:
>  	}
>  
>  start_service_thread:
> -	sprintf(thd_name, "mtip_svc_thd_%02d", index);
>  	dd->mtip_svc_handler = kthread_create_on_node(mtip_service_thread,
> -						dd, dd->numa_node, "%s",
> -						thd_name);
> +						dd, dd->numa_node,
> +						"mtip_svc_thd_%02d", index);
>  
>  	if (IS_ERR(dd->mtip_svc_handler)) {
>  		dev_err(&dd->pdev->dev, "service thread failed to start\n");

Re: [PATCH] mtip32xx: use formatting capability of kthread_create_on_node

[Jens Axboe]

On 11/20/2015 02:46 AM, Rasmus Villemoes wrote:
> kthread_create_on_node takes format+args, so there's no need to do the
> pretty-printing in advance. Moreover, "mtip_svc_thd_99" (including its
> '\0') only just fits in 16 bytes, so if index could ever go above 99
> we'd have a stack buffer overflow.

Applied, thanks.

-- 
Jens Axboe