Fix UTS corruption during clone(CLONE_NEWUTS)
Alexey Dobriyan [Wed, 19 Sep 2007 05:46:27 +0000 (22:46 -0700)]
struct utsname is copied from master one without any exclusion.

Here is sample output from one proggie doing

sethostname("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
sethostname("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");

and another

clone(,, CLONE_NEWUTS, ...)
uname()

hostname = 'aaaaaaaaaaaaaaaaaaaaaaaaabbbbb'
hostname = 'bbbaaaaaaaaaaaaaaaaaaaaaaaaaaa'
hostname = 'aaaaaaaabbbbbbbbbbbbbbbbbbbbbb'
hostname = 'aaaaaaaaaaaaaaaaaaaaaaaaaabbbb'
hostname = 'aaaaaaaaaaaaaaaaaaaaaaaaaaaabb'
hostname = 'aaabbbbbbbbbbbbbbbbbbbbbbbbbbb'
hostname = 'bbbbbbbbbbbbbbbbaaaaaaaaaaaaaa'

Hostname is sometimes corrupted.

Yes, even _the_ simplest namespace activity had bug in it. :-(

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/utsname.c

index 9d8180a..816d7b2 100644 (file)
@@ -28,7 +28,9 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
        if (!ns)
                return ERR_PTR(-ENOMEM);
 
+       down_read(&uts_sem);
        memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+       up_read(&uts_sem);
        kref_init(&ns->kref);
        return ns;
 }