oss-sec mailing list archives
Re: [PATCH 1/1] userns: unshare_userns(&cred) should not populate cred on failure
From: ebiederm () xmission com (Eric W. Biederman)
Date: Tue, 06 Aug 2013 13:56:41 -0700
Oleg Nesterov <oleg () redhat com> writes:
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.
Doh! Reviewed-by: "Eric W. Biederman" <ebiederm () xmission com>
Cc: stable () vger kernel org Signed-off-by: Oleg Nesterov <oleg () redhat com> --- kernel/user_namespace.c | 13 +++++++++---- 1 files changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index d8c30db..6e50a44 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 user_namespace *ns)
Current thread:
- CLONE_NEWUSER local DoS Petr Matousek (Aug 06)
- Re: CLONE_NEWUSER local DoS Kurt Seifried (Aug 06)
- Re: CLONE_NEWUSER local DoS Oleg Nesterov (Aug 06)
- [PATCH 0/1] (Was: CLONE_NEWUSER local DoS) Oleg Nesterov (Aug 06)
- [PATCH 1/1] userns: unshare_userns(&cred) should not populate cred on failure Oleg Nesterov (Aug 06)
- Re: [PATCH 1/1] userns: unshare_userns(&cred) should not populate cred on failure Andy Lutomirski (Aug 06)
- Re: [PATCH 1/1] userns: unshare_userns(&cred) should not populate cred on failure Eric W. Biederman (Aug 06)
- Re: [PATCH 0/1] (Was: CLONE_NEWUSER local DoS) Petr Matousek (Aug 07)
- [PATCH 0/1] (Was: CLONE_NEWUSER local DoS) Oleg Nesterov (Aug 06)
- Re: CLONE_NEWUSER local DoS Andy Lutomirski (Aug 06)
- Re: CLONE_NEWUSER local DoS Oleg Nesterov (Aug 06)