Patch "autofs: Fix automounts by using current_real_cred()->uid" has been added to the 4.8-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    autofs:  Fix automounts by using current_real_cred()->uid

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     autofs-fix-automounts-by-using-current_real_cred-uid.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 069d5ac9ae0d271903cc4607890616418118379a Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Fri, 30 Sep 2016 11:28:05 -0500
Subject: autofs:  Fix automounts by using current_real_cred()->uid

From: Eric W. Biederman <ebiederm@xmission.com>

commit 069d5ac9ae0d271903cc4607890616418118379a upstream.

Seth Forshee reports that in 4.8-rcN some automounts are failing
because the requesting the automount changed.

The relevant call path is:
follow_automount()
    ->d_automount
    autofs4_d_automount
       autofs4_mount_wait
           autofs4_wait

In autofs4_wait wq_uid and wq_gid are set to current_uid() and
current_gid respectively.  With follow_automount now overriding creds
uid that we export to userspace changes and that breaks existing
setups.

To remove the regression set wq_uid and wq_gid from
current_real_cred()->uid and current_real_cred()->gid respectively.
This restores the current behavior as current->real_cred is identical
to current->cred except when override creds are used.

Fixes: aeaa4a79ff6a ("fs: Call d_automount with the filesystems creds")
Reported-by: Seth Forshee <seth.forshee@canonical.com>
Tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/autofs4/waitq.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -431,8 +431,8 @@ int autofs4_wait(struct autofs_sb_info *
 		memcpy(&wq->name, &qstr, sizeof(struct qstr));
 		wq->dev = autofs4_get_dev(sbi);
 		wq->ino = autofs4_get_ino(sbi);
-		wq->uid = current_uid();
-		wq->gid = current_gid();
+		wq->uid = current_real_cred()->uid;
+		wq->gid = current_real_cred()->gid;
 		wq->pid = pid;
 		wq->tgid = tgid;
 		wq->status = -EINTR; /* Status return if interrupted */


Patches currently in stable-queue which might be from ebiederm@xmission.com are

queue-4.8/autofs-fix-automounts-by-using-current_real_cred-uid.patch