On 08/04, Peter Zijlstra wrote:
>
> +static int f_setown_ex(struct file *filp, unsigned long arg)
> +{
> + struct f_owner_ex * __user owner_p = (void * __user)arg;
> + struct f_owner_ex owner;
> + struct pid *pid;
> + int type;
> + int ret;
> +
> + ret = copy_from_user(&owner, owner_p, sizeof(owner));
> + if (ret)
> + return ret;
> +
> + switch (owner.type) {
> + case F_OWNER_TID:
> + type = PIDTYPE_MAX;
> + break;
> +
> + case F_OWNER_PID:
> + type = PIDTYPE_PID;
> + break;
> +
> + case F_OWNER_GID:
> + type = PIDTYPE_PGID;
> + break;
> + }
Note that send_sigio()->do_each_pid_task(type) must use the valid
type < PIDTYPE_MAX, or we can crash/etc.
This means f_setown_ex() should be careful with the wrong owner->type,
the switch() above needs
default:
return -EINVAL;
> + rcu_read_lock();
> + pid = find_vpid(owner.pid);
> + ret = __f_setown(filp, pid, type, 1);
> + rcu_read_unlock();
> +
> + return ret;
Perhaps it makes sense to return -ESRCH if owner.pid && !pid, not
sure.
> @@ -474,16 +540,23 @@ void send_sigio(struct fown_struct *fown
> struct task_struct *p;
> enum pid_type type;
> struct pid *pid;
> + int group = 1;
>
> read_lock(&fown->lock);
> +
> type = fown->pid_type;
> + if (type == PIDTYPE_MAX) {
> + group = 0;
> + type = PIDTYPE_PID;
> + }
And send_sigurg() needs the same change. I am not sure we should teach
send_sigurg_to_task() to handle the F_OWNER_TID, but we must ensure
send_sigurg()->do_each_pid_task() won't be called with PIDTYPE_MAX.
Otherwise, personally I think this is what we need to solve the problem.
Oleg.
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