Patch "fsnotify: pin both inode and vfsmount mark" has been added to the 4.14-stable tree

Patch "fsnotify: pin both inode and vfsmount mark" has been added to the 4.14-stable tree

[gregkh]

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

    fsnotify: pin both inode and vfsmount mark

to the 4.14-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:
     fsnotify-pin-both-inode-and-vfsmount-mark.patch
and it can be found in the queue-4.14 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 0d6ec079d6aaa098b978d6395973bb027c752a03 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Mon, 30 Oct 2017 21:14:55 +0100
Subject: fsnotify: pin both inode and vfsmount mark

From: Miklos Szeredi <mszeredi@redhat.com>

commit 0d6ec079d6aaa098b978d6395973bb027c752a03 upstream.

We may fail to pin one of the marks in fsnotify_prepare_user_wait() when
dropping the srcu read lock, resulting in use after free at the next
iteration.

Solution is to store both marks in iter_info instead of just the one we'll
be sending the event for.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 9385a84d7e1f ("fsnotify: Pass fsnotify_iter_info into handle_event handler")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/notify/fsnotify.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -335,6 +335,13 @@ int fsnotify(struct inode *to_tell, __u3
 						    struct fsnotify_mark, obj_list);
 			vfsmount_group = vfsmount_mark->group;
 		}
+		/*
+		 * Need to protect both marks against freeing so that we can
+		 * continue iteration from this place, regardless of which mark
+		 * we actually happen to send an event for.
+		 */
+		iter_info.inode_mark = inode_mark;
+		iter_info.vfsmount_mark = vfsmount_mark;
 
 		if (inode_group && vfsmount_group) {
 			int cmp = fsnotify_compare_groups(inode_group,
@@ -348,9 +355,6 @@ int fsnotify(struct inode *to_tell, __u3
 			}
 		}
 
-		iter_info.inode_mark = inode_mark;
-		iter_info.vfsmount_mark = vfsmount_mark;
-
 		ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask,
 				    data, data_is, cookie, file_name,
 				    &iter_info);


Patches currently in stable-queue which might be from mszeredi@redhat.com are

queue-4.14/fsnotify-clean-up-fsnotify_prepare-finish_user_wait.patch
queue-4.14/fsnotify-fix-pinning-group-in-fsnotify_prepare_user_wait.patch
queue-4.14/fanotify-fix-fsnotify_prepare_user_wait-failure.patch
queue-4.14/fsnotify-pin-both-inode-and-vfsmount-mark.patch
queue-4.14/ovl-put-upperdentry-if-ovl_check_origin-fails.patch