[PATCH] [SCSI] libsas: fix test for negative unsigned and typos

[PATCH] [SCSI] libsas: fix test for negative unsigned and typos

[roel kluin]

unsigned req->data_len cannot be negative, and fix typo

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
I am not sure whether this is what was intended, please review.

diff --git a/drivers/scsi/libsas/sas_host_smp.c b/drivers/scsi/libsas/sas_host_smp.c
index 16f9312..6eb0779 100644
--- a/drivers/scsi/libsas/sas_host_smp.c
+++ b/drivers/scsi/libsas/sas_host_smp.c
@@ -199,12 +199,12 @@ int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
 		break;
 
 	case SMP_DISCOVER:
-		req->data_len =- 16;
-		if (req->data_len < 0) {
+		if (req->data_len < 15) {
 			req->data_len = 0;
 			error = -EINVAL;
 			goto out;
 		}
+		req->data_len -= 16;
 		resp_data_len -= 56;
 		sas_host_smp_discover(sas_ha, resp_data, req_data[9]);
 		break;
@@ -215,12 +215,12 @@ int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
 		break;
 
 	case SMP_REPORT_PHY_SATA:
-		req->data_len =- 16;
-		if (req->data_len < 0) {
+		if (req->data_len < 15) {
 			req->data_len = 0;
 			error = -EINVAL;
 			goto out;
 		}
+		req->data_len -= 16;
 		resp_data_len -= 60;
 		sas_report_phy_sata(sas_ha, resp_data, req_data[9]);
 		break;
@@ -238,12 +238,12 @@ int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
 		break;
 
 	case SMP_PHY_CONTROL:
-		req->data_len =- 44;
-		if (req->data_len < 0) {
+		if (req->data_len < 43) {
 			req->data_len = 0;
 			error = -EINVAL;
 			goto out;
 		}
+		req->data_len -= 44;
 		resp_data_len -= 8;
 		sas_phy_control(sas_ha, req_data[9], req_data[10],
 				req_data[32] >> 4, req_data[33] >> 4,

Re: [PATCH] [SCSI] libsas: fix test for negative unsigned and typos

[James Bottomley]

On Sat, 2008-11-29 at 11:31 -0500, roel kluin wrote:
> unsigned req->data_len cannot be negative, and fix typo
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
> I am not sure whether this is what was intended, please review.

I think it was.  The fix looks like we need it.  However:

> diff --git a/drivers/scsi/libsas/sas_host_smp.c b/drivers/scsi/libsas/sas_host_smp.c
> index 16f9312..6eb0779 100644
> --- a/drivers/scsi/libsas/sas_host_smp.c
> +++ b/drivers/scsi/libsas/sas_host_smp.c
> @@ -199,12 +199,12 @@ int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
>  		break;
>  
>  	case SMP_DISCOVER:
> -		req->data_len =- 16;
> -		if (req->data_len < 0) {
> +		if (req->data_len < 15) {
>  			req->data_len = 0;
>  			error = -EINVAL;
>  			goto out;
>  		}

What I don't like about this code is the magic numbers for lengths.
This patch now doubles them (and makes them even more magic by having <
n-1).  How about fixing it like this instead:

if ((int)req->data_len < 0) {
...

That way the signed comparison just works if there was a negative
overflow?

Thanks,

James