nullfs: do not allow to mount a vnode over itself

This causes recursion in VFS that is not worth handling.

PR:	275570
Reported by:	Alex S <iwtcex@gmail.com>
Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D57043

This commit is contained in:

Konstantin Belousov

2026-05-17 01:16:45 +03:00

parent 363ea40c76

commit 7bdf2b5d5f

1 changed files with 8 additions and 0 deletions

									
										sys/fs/nullfs/null_vfsops.c
									
		+8
		
												View File
												
				@@ -151,6 +151,14 @@ nullfs_mount(struct mount *mp)

					 */

					lowerrootvp = ndp->ni_vp;

					/*

					 * Do not allow to mount a vnode over itself.

					 */

					if (mp->mnt_vnodecovered == lowerrootvp) {

						vput(lowerrootvp);

						return (EDEADLK);

					}

					/*

					 * Check multi null mount to avoid `lock against myself' panic.

					 */