linux-kernel - [PATCH] Fix UTS corruption during clone(CLONE

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Message-ID: <20070914145730.GB27986@localhost.sw.ru>
Date:	Fri, 14 Sep 2007 18:57:30 +0400
From:	Alexey Dobriyan <adobriyan@...ru>
To:	akpm@...l.org
Cc:	linux-kernel@...r.kernel.org, devel@...nvz.org
Subject: [PATCH] Fix UTS corruption during clone(CLONE_NEWUTS)

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@...ru>
---

 kernel/utsname.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -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;
 }

-
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