Patch "ceph: fix error handling in ceph_read_iter" has been added to the 4.8-stable tree

Patch "ceph: fix error handling in ceph_read_iter" has been added to the 4.8-stable tree

[gregkh]

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

    ceph: fix error handling in ceph_read_iter

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:
     ceph-fix-error-handling-in-ceph_read_iter.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 0d7718f666be181fda1ba2d08f137d87c1419347 Mon Sep 17 00:00:00 2001
From: Nikolay Borisov <kernel@kyup.com>
Date: Mon, 10 Oct 2016 15:38:18 +0300
Subject: ceph: fix error handling in ceph_read_iter

From: Nikolay Borisov <kernel@kyup.com>

commit 0d7718f666be181fda1ba2d08f137d87c1419347 upstream.

In case __ceph_do_getattr returns an error and the retry_op in
ceph_read_iter is not READ_INLINE, then it's possible to invoke
__free_page on a page which is NULL, this naturally leads to a crash.
This can happen when, for example, a process waiting on a MDS reply
receives sigterm.

Fix this by explicitly checking whether the page is set or not.

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1272,7 +1272,8 @@ again:
 		statret = __ceph_do_getattr(inode, page,
 					    CEPH_STAT_CAP_INLINE_DATA, !!page);
 		if (statret < 0) {
-			 __free_page(page);
+			if (page)
+				__free_page(page);
 			if (statret == -ENODATA) {
 				BUG_ON(retry_op != READ_INLINE);
 				goto again;


Patches currently in stable-queue which might be from kernel@kyup.com are

queue-4.8/fs-super.c-fix-race-between-freeze_super-and-thaw_super.patch
queue-4.8/ceph-fix-error-handling-in-ceph_read_iter.patch