On Wed, Dec 09, 2020 at 07:21:00PM +0800, Yahu Gao wrote:
> Get the staus of task from the pointer of proc inode directly is not
> safe. The function get_proc_task make it happen in RCU protection.
This is completely broken, get_proc_task() acquires a reference to
task_struct; your patch is an instant leak.
> Signed-off-by: Yahu Gao <yahu.gao@xxxxxxxxxxxxx>
> ---
> fs/proc/base.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 1bc9bcdef09f..05f33bb35067 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1994,7 +1994,7 @@ static int pid_revalidate(struct dentry *dentry, unsigned int flags)
>
> static inline bool proc_inode_is_dead(struct inode *inode)
> {
> - return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
> + return !get_proc_task(inode);
> }
>
> int pid_delete_dentry(const struct dentry *dentry)
> --
> 2.25.1
>
