eventfs: Fix a possible null pointer dereference in eventfs_find_events()

In function eventfs_find_events,there is a potential null pointer
that may be caused by calling update_events_attr which will perform
some operations on the members of the ei struct when ei is NULL.

Hence,When ei->is_freed is set,return NULL directly.

Link: https://lore.kernel.org/linux-trace-kernel/20240513053338.63017-1-hao.ge@linux.dev
Cc: stable@vger.kernel.org
Fixes: 8186fff7ab64 ("tracefs/eventfs: Use root and instance inodes as default ownership")
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index a878cea70f4c9077612e0eefea159746e729fe5c..0256afdd4acfb553a189fc3f9e1f4a054650ebe8 100644 (file)
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -345,10 +345,9 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
                 * If the ei is being freed, the ownership of the children
                 * doesn't matter.
                 */
-               if (ei->is_freed) {
-                       ei = NULL;
-                       break;
-               }
+               if (ei->is_freed)
+                       return NULL;
+
                // Walk upwards until you find the events inode
        } while (!ei->is_events);