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SubjectRe: namespaces: Out-of-bounds array access
On Fri, 06 Jan 2012 01:18:47 +0100
Richard Weinberger <richard@nod.at> wrote:

> Hi!
>
> While searching a completely different bug I've found this problem:
> If CONFIG_NET_NS, CONFIG_UTS_NS and CONFIG_IPC_NS are disabled, ns_entries[]
> becomes empty and things like ns_entries[ARRAY_SIZE(ns_entries) - 1] will explode.
>

Presumably this will fix it:

--- a/fs/proc/namespaces.c~a
+++ a/fs/proc/namespaces.c
@@ -156,15 +156,15 @@ static struct dentry *proc_ns_dir_lookup
if (!ptrace_may_access(task, PTRACE_MODE_READ))
goto out;

- last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
- for (entry = ns_entries; entry <= last; entry++) {
+ last = &ns_entries[ARRAY_SIZE(ns_entries)];
+ for (entry = ns_entries; entry < last; entry++) {
if (strlen((*entry)->name) != len)
continue;
if (!memcmp(dentry->d_name.name, (*entry)->name, len))
break;
}
error = ERR_PTR(-ENOENT);
- if (entry > last)
+ if (entry == last)
goto out;

error = proc_ns_instantiate(dir, dentry, task, *entry);
_
But I wonder why we compile this file at all when ns_entries[] is
empty?


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