Re: [syzbot] [pm?] KASAN: use-after-free Read in netdev_unregister_kobject

[Hillf Danton]

On Mon, 22 Apr 2024 08:35:25 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    3cdb45594619 Merge tag 's390-6.9-4' of git://git.kernel.or..
> git tree:       upstream
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=144067cb180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  3cdb45594619

--- x/net/bluetooth/bnep/core.c
+++ y/net/bluetooth/bnep/core.c
@@ -659,7 +659,7 @@ int bnep_del_connection(struct bnep_conn
 	if (req->flags & ~valid_flags)
 		return -EINVAL;
 
-	down_read(&bnep_session_sem);
+	down_write(&bnep_session_sem);
 
 	s = __bnep_get_session(req->dst);
 	if (s) {
@@ -668,7 +668,7 @@ int bnep_del_connection(struct bnep_conn
 	} else
 		err = -ENOENT;
 
-	up_read(&bnep_session_sem);
+	up_write(&bnep_session_sem);
 	return err;
 }
 
--