2018-06-12 04:17:21

by Zhouyang Jia

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

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 <[email protected]>
---
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

2018-06-12 05:32:50

by Amir Goldstein

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

On Tue, Jun 12, 2018 at 7:16 AM, Zhouyang Jia <[email protected]> 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 <[email protected]>
> ---
> 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
>

2018-06-12 14:49:58

by Jan Kara

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

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 <[email protected]>
> ---
> 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 <[email protected]>
SUSE Labs, CR