Subject: + userns-unshare_usernscred-should-not-populate-cred-on-failure.patch 
added to -mm tree
To: 
[email protected],[email protected],[email protected],[email protected],[email protected],[email protected]
From: [email protected]
Date: Tue, 06 Aug 2013 15:44:45 -0700


The patch titled
     Subject: userns: unshare_userns(&cred) should not populate cred on failure
has been added to the -mm tree.  Its filename is
     userns-unshare_usernscred-should-not-populate-cred-on-failure.patch

This patch should soon appear at
    
http://ozlabs.org/~akpm/mmots/broken-out/userns-unshare_usernscred-should-not-populate-cred-on-failure.patch
and later at
    
http://ozlabs.org/~akpm/mmotm/broken-out/userns-unshare_usernscred-should-not-populate-cred-on-failure.patch

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------------------------------------------------------
From: Oleg Nesterov <[email protected]>
Subject: userns: unshare_userns(&cred) should not populate cred on failure

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 <[email protected]>
Cc: Petr Matousek <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Reviewed-by: Andy Lutomirski <[email protected]>
Cc: David Howells <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 kernel/user_namespace.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff -puN 
kernel/user_namespace.c~userns-unshare_usernscred-should-not-populate-cred-on-failure
 kernel/user_namespace.c
--- 
a/kernel/user_namespace.c~userns-unshare_usernscred-should-not-populate-cred-on-failure
+++ a/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)
_

Patches currently in -mm which might be from [email protected] are

userns-unshare_usernscred-should-not-populate-cred-on-failure.patch
x86-get_unmapped_area-use-proper-mmap-base-for-bottom-up-direction.patch
include-linux-schedh-dont-use-task-pid-tgid-in-same_thread_group-has_group_leader_pid.patch
mm-mempolicy-turn-vma_set_policy-into-vma_dup_policy.patch
mm-shift-vm_grows-check-from-mmap_region-to-do_mmap_pgoff-v2.patch
mm-do_mmap_pgoff-cleanup-the-usage-of-file_inode.patch
mm-mmap_region-kill-correct_wcount-inode-use-allow_write_access.patch
kernel-wide-fix-missing-validations-on-__get-__put-__copy_to-__copy_from_user.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
signals-eventpoll-set-saved_sigmask-at-the-start.patch
move-exit_task_namespaces-outside-of-exit_notify-fix.patch
exec-introduce-exec_binprm-for-depth-==-0-code.patch
exec-kill-int-depth-in-search_binary_handler.patch
exec-proc_exec_connector-should-be-called-only-once.patch
exec-move-allow_write_access-fput-to-exec_binprm.patch
exec-kill-load_binary-=-null-check-in-search_binary_handler.patch
exec-cleanup-the-config_modules-logic.patch
exec-dont-retry-if-request_module-fails.patch
exec-cleanup-the-error-handling-in-search_binary_handler.patch
linux-next.patch

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