linux-kernel - [PATCH 5.4 140/270] kernfs: do not call fsnotify() with name without a parent

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Message-Id: <20200817143802.784782913@linuxfoundation.org>
Date:   Mon, 17 Aug 2020 17:15:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tejun Heo <tj@...nel.org>,
        Amir Goldstein <amir73il@...il.com>, Jan Kara <jack@...e.cz>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 140/270] kernfs: do not call fsnotify() with name without a parent

From: Amir Goldstein <amir73il@...il.com>

[ Upstream commit 9991bb84b27a2594187898f261866cfc50255454 ]

When creating an FS_MODIFY event on inode itself (not on parent)
the file_name argument should be NULL.

The change to send a non NULL name to inode itself was done on purpuse
as part of another commit, as Tejun writes: "...While at it, supply the
target file name to fsnotify() from kernfs_node->name.".

But this is wrong practice and inconsistent with inotify behavior when
watching a single file.  When a child is being watched (as opposed to the
parent directory) the inotify event should contain the watch descriptor,
but not the file name.

Fixes: df6a58c5c5aa ("kernfs: don't depend on d_find_any_alias()...")
Link: https://lore.kernel.org/r/20200708111156.24659-5-amir73il@gmail.com
Acked-by: Tejun Heo <tj@...nel.org>
Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Amir Goldstein <amir73il@...il.com>
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/kernfs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e8c792b496166..c35bbaa194862 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -912,7 +912,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
 		}
 
 		fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
-			 &name, 0);
+			 NULL, 0);
 		iput(inode);
 	}
 
-- 
2.25.1