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Date: Fri, 16 Aug 2013 15:34:03 -0700
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: Oleg Nesterov <oleg@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 101/133] userns: unshare_userns(&cred) should not populate cred on failure
3.8.13.7 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Oleg Nesterov <oleg@...hat.com>
commit 6160968cee8b90a5dd95318d716e31d7775c4ef3 upstream.
unshare_userns(new_cred) does *new_cred = prepare_creds() before
create_user_ns() which can fail. However, the caller expects that
it doesn't need to take care of new_cred if unshare_userns() fails.
We could change the single caller, sys_unshare(), but I think it
would be more clean to avoid the side effects on failure, so with
this patch unshare_userns() does put_cred() itself and initializes
*new_cred only if create_user_ns() succeeeds.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Reviewed-by: Andy Lutomirski <luto@...capital.net>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
kernel/user_namespace.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index f359dc7..38ae0f5 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -105,16 +105,21 @@ int create_user_ns(struct cred *new)
int unshare_userns(unsigned long unshare_flags, struct cred **new_cred)
{
struct cred *cred;
+ int err = -ENOMEM;
if (!(unshare_flags & CLONE_NEWUSER))
return 0;
cred = prepare_creds();
- if (!cred)
- return -ENOMEM;
+ if (cred) {
+ err = create_user_ns(cred);
+ if (err)
+ put_cred(cred);
+ else
+ *new_cred = cred;
+ }
- *new_cred = cred;
- return create_user_ns(cred);
+ return err;
}
void free_user_ns(struct kref *kref)
--
1.8.1.2
--
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