[3.13.y.z extended stable] Patch "aio: fix aio request leak when events are reaped by userspace" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    aio: fix aio request leak when events are reaped by userspace

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From ea0ec5d5acd0935ee8e9ad3c2d60fd40977d04ae Mon Sep 17 00:00:00 2001
From: Benjamin LaHaise <bcrl at kvack.org>
Date: Tue, 24 Jun 2014 13:12:55 -0400
Subject: aio: fix aio request leak when events are reaped by userspace

commit f8567a3845ac05bb28f3c1b478ef752762bd39ef upstream.

The aio cleanups and optimizations by kmo that were merged into the 3.10
tree added a regression for userspace event reaping.  Specifically, the
reference counts are not decremented if the event is reaped in userspace,
leading to the application being unable to submit further aio requests.
This patch applies to 3.12+.  A separate backport is required for 3.10/3.11.
This issue was uncovered as part of CVE-2014-0206.

Signed-off-by: Benjamin LaHaise <bcrl at kvack.org>
Cc: Kent Overstreet <kmo at daterainc.com>
Cc: Mateusz Guzik <mguzik at redhat.com>
Cc: Petr Matousek <pmatouse at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/aio.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 04cd768..e9566f2 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1007,6 +1007,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)

 	/* everything turned out well, dispose of the aiocb. */
 	kiocb_free(iocb);
+	put_reqs_available(ctx, 1);

 	/*
 	 * We have to order our ring_info tail store above and test
@@ -1086,8 +1087,6 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	flush_dcache_page(ctx->ring_pages[0]);

 	pr_debug("%li  h%u t%u\n", ret, head, tail);
-
-	put_reqs_available(ctx, ret);
 out:
 	mutex_unlock(&ctx->ring_lock);

--
1.9.1