Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [PATCH] do_task_stat: don't use task_pid_nr_ns() lockless | Date | Sat, 17 Nov 2007 13:11:00 -0700 |
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Oleg Nesterov <oleg@tv-sign.ru> writes:
> Without rcu/tasklist/siglock lock task_pid_nr_ns() may read the freed memory, > move the callsite under ->siglock. > > Sadly, we can report pid == 0 if the task was detached.
We only get detached in release_task so it is a pretty small window where we can return pid == 0. Usually get_task_pid will fail first and we will return -ESRCH. Still the distance from open to
There is another bug in here as well. current->nsproxy->pid_ns is wrong. What we want is: ns = dentry->d_sb->s_fs_info;
Otherwise we will have file descriptor passing races and the like.
We could also do: proc_pid(inode) to get the pid, which is a little more race free, and will prevent us from returning pid == 0.
In either event it looks like we need to implement some proper file operations for these proc files, maybe even going to seq file status.
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