[PATCH] fsnotify: add error handling for kmem_cache_create

[PATCH] fsnotify: add error handling for kmem_cache_create

[Zhouyang Jia]

When kmem_cache_create fails, the lack of error-handling code may
cause unexpected results.

This patch adds error-handling code after calling kmem_cache_create.

Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
---
 fs/notify/dnotify/dnotify.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 63a1ca4..216b411 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -387,6 +387,9 @@ static int __init dnotify_init(void)
 	dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
 	dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC);
 
+	if (!dnotify_struct_cache || !dnotify_mark_cache)
+		return -ENOMEM;
+
 	dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops);
 	if (IS_ERR(dnotify_group))
 		panic("unable to allocate fsnotify group for dnotify\n");
-- 
2.7.4

Re: [PATCH] fsnotify: add error handling for kmem_cache_create

[Amir Goldstein]

On Tue, Jun 12, 2018 at 7:16 AM, Zhouyang Jia <jiazhouyang09@gmail.com> wrote:
> When kmem_cache_create fails, the lack of error-handling code may
> cause unexpected results.
>
> This patch adds error-handling code after calling kmem_cache_create.
>
> Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
> ---
>  fs/notify/dnotify/dnotify.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
> index 63a1ca4..216b411 100644
> --- a/fs/notify/dnotify/dnotify.c
> +++ b/fs/notify/dnotify/dnotify.c
> @@ -387,6 +387,9 @@ static int __init dnotify_init(void)
>         dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
>         dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC);
>
> +       if (!dnotify_struct_cache || !dnotify_mark_cache)
> +               return -ENOMEM;
> +

If only one failed need to free the other.

>         dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops);
>         if (IS_ERR(dnotify_group))
>                 panic("unable to allocate fsnotify group for dnotify\n");
> --
> 2.7.4
>

Re: [PATCH] fsnotify: add error handling for kmem_cache_create

[Jan Kara]

On Tue 12-06-18 12:16:04, Zhouyang Jia wrote:
> When kmem_cache_create fails, the lack of error-handling code may
> cause unexpected results.
> 
> This patch adds error-handling code after calling kmem_cache_create.
> 
> Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
> ---
>  fs/notify/dnotify/dnotify.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
> index 63a1ca4..216b411 100644
> --- a/fs/notify/dnotify/dnotify.c
> +++ b/fs/notify/dnotify/dnotify.c
> @@ -387,6 +387,9 @@ static int __init dnotify_init(void)
>  	dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
>  	dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC);
>  
> +	if (!dnotify_struct_cache || !dnotify_mark_cache)
> +		return -ENOMEM;
> +

Caches are allocated with SLAB_PANIC - i.e., we panic the system if caches
cannot be created. And that's intended since something is really wrong with
the system in that case. So this check is pointless.

								Honza

>  	dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops);
>  	if (IS_ERR(dnotify_group))
>  		panic("unable to allocate fsnotify group for dnotify\n");
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR