Messages in this thread | | | Date | Tue, 31 Jul 2012 14:30:07 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [Announce] Checkpoint-restore tool v0.1 |
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On Tue, Jul 31, 2012 at 12:21:58PM +0200, richard -rw- weinberger wrote: > On Tue, Jul 31, 2012 at 12:16 PM, Cyrill Gorcunov <gorcunov@openvz.org> wrote: > > On Tue, Jul 31, 2012 at 12:08:22PM +0200, richard -rw- weinberger wrote: > >> On Tue, Jul 31, 2012 at 11:54 AM, Pavel Emelyanov <xemul@parallels.com> wrote: > >> >> Yeah, but I fear it's not that easy. > >> >> We'd have to change crtools to work without ptrace(). > >> > > >> > Well, this is hard. Using ptrace saved us from having many special-purpose > >> > APIs for dumping various stuff (there will be an article about it). Thus I > >> > don't know which way is simpler -- stop using ptrace or teach ptrece to allow > >> > several tracers to attach to one task %) > >> > >> Allowing multiple tracers in a safe way is IMHO even more harder. > >> > >> BTW: While reading prctl_set_mm() I noticed two things. > >> 1. Why isn't the return value of find_vma() verified? > > > > prctl_set_mm > > vma = find_vma(mm, addr); > > ... > > if (!vma) { > > error = -EFAULT; > > goto out; > > } > > > > these values are used in procfs statistics only. So I don't get > > which verify you mean here. > > If I do PR_SET_MM_START_BRK the if(!vma) will never be executed because > there a break in case PR_SET_MM_START_BRK.
Yes, and this is done by purpose, since we need to setup _completely_ new memory map on restore procedure.
There is a minimal check for value being sane
if (addr >= TASK_SIZE || addr < mmap_min_addr) return -EINVAL;
and the address belongs to mm::start_data|end_data area. But sure, better to add checks that at least code/data areas do exist, otherwise the proc output will not reflect the real state of memory maps.
Cyrill
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