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-rw-r--r--fs/dnotify.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/dnotify.c b/fs/dnotify.c
index 28d01ed66de0..eaecc4cfe540 100644
--- a/fs/dnotify.c
+++ b/fs/dnotify.c
@@ -20,6 +20,7 @@
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
+#include <linux/file.h>
int dir_notify_enable __read_mostly = 1;
@@ -66,6 +67,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
struct dnotify_struct **prev;
struct inode *inode;
fl_owner_t id = current->files;
+ struct file *f;
int error = 0;
if ((arg & ~DN_MULTISHOT) == 0) {
@@ -92,6 +94,15 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
prev = &odn->dn_next;
}
+ rcu_read_lock();
+ f = fcheck(fd);
+ rcu_read_unlock();
+ /* we'd lost the race with close(), sod off silently */
+ /* note that inode->i_lock prevents reordering problems
+ * between accesses to descriptor table and ->i_dnotify */
+ if (f != filp)
+ goto out_free;
+
error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
if (error)
goto out_free;