Messages in this thread | | | Date | Wed, 23 Jun 2010 21:41:45 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] sanitize task->comm to avoid leaking escape codes |
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On 06/23, Kees Cook wrote: > > @@ -956,7 +957,15 @@ void set_task_comm(struct task_struct *tsk, char *buf) > */ > memset(tsk->comm, 0, TASK_COMM_LEN); > wmb();
Off-topic. I'd wish I could understand this barrier. Since the lockless reader doesn't do rmb() I don't see how this can help. OTOH, I don't understand why it is needed, we never change ->comm[TASK_COMM_LEN-1] == '0'.
> - strlcpy(tsk->comm, buf, sizeof(tsk->comm)); > + > + /* sanitize non-printable characters */ > + for (i = 0; buf[i] && i < (sizeof(tsk->comm) - 1); i++) { > + if (!isprint(buf[i])) > + tsk->comm[i] = '?'; > + else > + tsk->comm[i] = buf[i]; > + }
Personally I think this makes sense.
> -extern char *get_task_comm(char *to, struct task_struct *tsk); > +#define get_task_comm(buf, task) get_task_comm_size(buf, sizeof(buf), task) > +extern char *get_task_comm_size(char *to, size_t len, struct task_struct *tsk);
Oh, but this means that get_task_comm(ptr, task) doesn't work?
Oleg.
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