Patch "eventpoll: fix uninitialized variable in epoll_ctl" has been added to the 3.14-stable tree

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

    eventpoll: fix uninitialized variable in epoll_ctl

to the 3.14-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:
     eventpoll-fix-uninitialized-variable-in-epoll_ctl.patch
and it can be found in the queue-3.14 subdirectory.

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


>From c680e41b3a2e944185c74bf60531e3d316d3ecc4 Mon Sep 17 00:00:00 2001
From: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Date: Tue, 9 Sep 2014 14:50:51 -0700
Subject: eventpoll: fix uninitialized variable in epoll_ctl
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>

commit c680e41b3a2e944185c74bf60531e3d316d3ecc4 upstream.

When calling epoll_ctl with operation EPOLL_CTL_DEL, structure epds is
not initialized but ep_take_care_of_epollwakeup reads its event field.
When this unintialized field has EPOLLWAKEUP bit set, a capability check
is done for CAP_BLOCK_SUSPEND in ep_take_care_of_epollwakeup.  This
produces unexpected messages in the audit log, such as (on a system
running SELinux):

    type=AVC msg=audit(1408212798.866:410): avc:  denied
    { block_suspend } for  pid=7754 comm="dbus-daemon" capability=36
    scontext=unconfined_u:unconfined_r:unconfined_t
    tcontext=unconfined_u:unconfined_r:unconfined_t
    tclass=capability2 permissive=1

    type=SYSCALL msg=audit(1408212798.866:410): arch=c000003e syscall=233
    success=yes exit=0 a0=3 a1=2 a2=9 a3=7fffd4d66ec0 items=0 ppid=1
    pid=7754 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0
    fsgid=0 tty=(none) ses=3 comm="dbus-daemon"
    exe="/usr/bin/dbus-daemon"
    subj=unconfined_u:unconfined_r:unconfined_t key=(null)

("arch=c000003e syscall=233 a1=2" means "epoll_ctl(op=EPOLL_CTL_DEL)")

Remove use of epds in epoll_ctl when op == EPOLL_CTL_DEL.

Fixes: 4d7e30d98939 ("epoll: Add a flag, EPOLLWAKEUP, to prevent suspend while epoll events are ready")
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Arve Hjønnevåg <arve@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/eventpoll.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1852,7 +1852,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, in
 		goto error_tgt_fput;
 
 	/* Check if EPOLLWAKEUP is allowed */
-	ep_take_care_of_epollwakeup(&epds);
+	if (ep_op_has_event(op))
+		ep_take_care_of_epollwakeup(&epds);
 
 	/*
 	 * We have to check that the file structure underneath the file descriptor


Patches currently in stable-queue which might be from nicolas.iooss_linux@xxxxxxx are

queue-3.14/eventpoll-fix-uninitialized-variable-in-epoll_ctl.patch
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