[PATCH 1/1] xen: set error code on failures

[PATCH 1/1] xen: set error code on failures

[Pan Bian]

From: Pan Bian <bianpan2016@163.com>

The return variable rc is initialized with "-ENOMEM" outside the loop.
However, it is reset in the loop, and its value is not negative during 
the second or after repeat of the loop. If kzalloc() fails then, it will 
return 0. This patch fixes the bug, assigning "-ENOMEM" to rc when 
kzalloc() or alloc_page() returns NULL.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=189111

Signed-off-by: Pan Bian <bianpan2016@163.com>
---
 drivers/xen/gntalloc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index 7a47c4c..55ef246 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -130,15 +130,19 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
 	rc = -ENOMEM;
 	for (i = 0; i < op->count; i++) {
 		gref = kzalloc(sizeof(*gref), GFP_KERNEL);
-		if (!gref)
+		if (!gref) {
+			rc = -ENOMEM;
 			goto undo;
+		}
 		list_add_tail(&gref->next_gref, &queue_gref);
 		list_add_tail(&gref->next_file, &queue_file);
 		gref->users = 1;
 		gref->file_index = op->index + i * PAGE_SIZE;
 		gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO);
-		if (!gref->page)
+		if (!gref->page) {
+			rc = -ENOMEM;
 			goto undo;
+		}
 
 		/* Grant foreign access to the page. */
 		rc = gnttab_grant_foreign_access(op->domid,
-- 
1.9.1

Re: [PATCH 1/1] xen: set error code on failures

[Juergen Gross]

On 04/12/16 07:24, Pan Bian wrote:
> From: Pan Bian <bianpan2016@163.com>
> 
> The return variable rc is initialized with "-ENOMEM" outside the loop.
> However, it is reset in the loop, and its value is not negative during 
> the second or after repeat of the loop. If kzalloc() fails then, it will 
> return 0. This patch fixes the bug, assigning "-ENOMEM" to rc when 
> kzalloc() or alloc_page() returns NULL.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=189111
> 
> Signed-off-by: Pan Bian <bianpan2016@163.com>
> ---
>  drivers/xen/gntalloc.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
> index 7a47c4c..55ef246 100644
> --- a/drivers/xen/gntalloc.c
> +++ b/drivers/xen/gntalloc.c
> @@ -130,15 +130,19 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
>  	rc = -ENOMEM;

You can drop this now.

>  	for (i = 0; i < op->count; i++) {
>  		gref = kzalloc(sizeof(*gref), GFP_KERNEL);
> -		if (!gref)
> +		if (!gref) {
> +			rc = -ENOMEM;
>  			goto undo;
> +		}
>  		list_add_tail(&gref->next_gref, &queue_gref);
>  		list_add_tail(&gref->next_file, &queue_file);
>  		gref->users = 1;
>  		gref->file_index = op->index + i * PAGE_SIZE;
>  		gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO);
> -		if (!gref->page)
> +		if (!gref->page) {
> +			rc = -ENOMEM;
>  			goto undo;
> +		}
>  
>  		/* Grant foreign access to the page. */
>  		rc = gnttab_grant_foreign_access(op->domid,
> 


Juergen