From: Oleg Nesterov Date: Tue, 6 Aug 2013 17:38:55 +0000 (+0200) Subject: userns: unshare_userns(&cred) should not populate cred on failure X-Git-Url: https://git.stricted.de/?p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git;a=commitdiff_plain;h=c98ebcb618645d40cfec14b0534ff32126c114ce userns: unshare_userns(&cred) should not populate cred on failure 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 Reviewed-by: Andy Lutomirski Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index d8c30db06c5..6e50a44610e 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)