fanotify: fix FAN_Q_OVERFLOW case of fanotify_read()
If the FAN_Q_OVERFLOW bit set in event->mask, the fanotify event
metadata will not contain a valid file descriptor, but
copy_event_to_user() didn't check for that, and unconditionally does a
fd_install() on the file descriptor.
Which in turn will cause a BUG_ON() in __fd_install().
Introduced by commit 352e3b249284 ("fanotify: sanitize failure exits in
copy_event_to_user()")
Mea culpa - missed that path ;-/
Reported-by: Alex Shi <lkml.alex@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 721d692..6fcaeb8 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -258,7 +258,8 @@
if (ret)
goto out_close_fd;
- fd_install(fd, f);
+ if (fd != FAN_NOFD)
+ fd_install(fd, f);
return fanotify_event_metadata.event_len;
out_close_fd:
