[PATCH] fanotify: initialize permission event watchdog state

[PATCH] fanotify: initialize permission event watchdog state

[xuanqiang.luo]

From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

fanotify permission events are allocated with kmem_cache_alloc(), but
fanotify_alloc_perm_event() does not initialize watchdog_cnt.

The watchdog reads watchdog_cnt after the event is moved to access_list.
A stale value can make it warn too early or skip the warning.

Initialize watchdog_cnt when allocating a permission event.

Fixes: b8cf8fda522d ("fanotify: add watchdog for permission events")
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
---
 fs/notify/fanotify/fanotify.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index a3555bebad63e..b59f0aa43c4be 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -599,6 +599,7 @@ static struct fanotify_event *fanotify_alloc_perm_event(const void *data,
 	pevent->hdr.pad = 0;
 	pevent->hdr.len = 0;
 	pevent->state = FAN_EVENT_INIT;
+	pevent->watchdog_cnt = 0;
 	pevent->path = *path;
 	/* NULL ppos means no range info */
 	pevent->ppos = range ? &range->pos : NULL;
-- 
2.43.0

Re: [PATCH] fanotify: initialize permission event watchdog state

[Jan Kara]

On Fri 03-07-26 11:13:45, xuanqiang.luo@linux.dev wrote:
> From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
> 
> fanotify permission events are allocated with kmem_cache_alloc(), but
> fanotify_alloc_perm_event() does not initialize watchdog_cnt.
> 
> The watchdog reads watchdog_cnt after the event is moved to access_list.
> A stale value can make it warn too early or skip the warning.
> 
> Initialize watchdog_cnt when allocating a permission event.
> 
> Fixes: b8cf8fda522d ("fanotify: add watchdog for permission events")
> Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

Thanks. I've added the patch to my tree.

								Honza

> ---
>  fs/notify/fanotify/fanotify.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index a3555bebad63e..b59f0aa43c4be 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -599,6 +599,7 @@ static struct fanotify_event *fanotify_alloc_perm_event(const void *data,
>  	pevent->hdr.pad = 0;
>  	pevent->hdr.len = 0;
>  	pevent->state = FAN_EVENT_INIT;
> +	pevent->watchdog_cnt = 0;
>  	pevent->path = *path;
>  	/* NULL ppos means no range info */
>  	pevent->ppos = range ? &range->pos : NULL;
> -- 
> 2.43.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR