Messages in this thread | | | Date | Tue, 10 Nov 2009 18:04:53 +0100 | From | Oleg Nesterov <> | Subject | Re: + prctl-add-pr_set_proctitle_area-option.patch added to -mm tree |
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@@ -1424,6 +1424,28 @@ static void k_getrusage(struct task_stru } while (t != p); break; + case PR_SET_PROCTITLE_AREA: { + struct mm_struct *mm = current->mm; + unsigned long addr = arg2; + unsigned long len = arg3; + unsigned long end = arg2 + arg3; + + if (len > PAGE_SIZE) + return -EINVAL; + + if (addr >= end) + return -EINVAL; + + if (!access_ok(VERIFY_READ, addr, len)) + return -EFAULT; + + mutex_lock(&mm->arg_lock); + mm->arg_start = addr; + mm->arg_end = end; + mutex_unlock(&mm->arg_lock);
This looks like the merging error, I guess this code should go into sys_prct(), not k_getrusage().
The patch adds mm_struct->arg_lock mutex. Can't we reuse mm->mmap_sem? A bit ugly to have mm->arg_lock just to synchronize sys_prctl() and proc_pid_cmdline(), imho.
Yes, we can't do access_process_vm() under ->mmap_sem, but we can add the new helper, say, access_process_vm_locked(tsk, mm, ...) which does the actual work. Then proc_pid_cmdline() can take mmap_sem for reading, read arg_start/arg_end and call access_process_vm_locked().
No?
Oleg.
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