Messages in this thread Patch in this message | | | Date | Wed, 23 Sep 2015 18:57:57 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [patch] mm, oom: remove task_lock protecting comm printing |
| |
On (09/23/15 18:50), Sergey Senozhatsky wrote: > On (09/23/15 11:43), Michal Hocko wrote: > [..] > > > > the previous name was already null terminated, > > > > > > Yeah, but if the old name is shorter than the new one, set_task_comm() > > > overwrites the terminating null of the old name before writing the new > > > terminating null, so there is a short time window during which tsk->comm > > > might be not null-terminated, no? > > > > Not really: > > case PR_SET_NAME: > > comm[sizeof(me->comm) - 1] = 0; > > if (strncpy_from_user(comm, (char __user *)arg2, > > sizeof(me->comm) - 1) < 0) > > return -EFAULT; > > > > So it first writes the terminating 0 and only then starts copying. > > right.
... no right. that should have been
me->comm[sizeof(me->comm) - 1] = 0;
to be save. no?
> hm, shouldn't set_task_comm()->__set_task_comm() do the same?
or something like this instead
---
fs/exec.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/fs/exec.c b/fs/exec.c index b06623a..d7d2de0 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1072,6 +1072,7 @@ EXPORT_SYMBOL_GPL(get_task_comm); void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) { + tsk->comm[sizeof(tsk->comm) - 1] = 0; task_lock(tsk); trace_task_rename(tsk, buf); strlcpy(tsk->comm, buf, sizeof(tsk->comm));
| |