Author: kib
Date: Fri Feb 8 08:17:31 2019
New Revision: 343898
URL: https://svnweb.freebsd.org/changeset/base/343898
Log:
Before using VTONULL(), check that the covered vnode belongs to nullfs.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/fs/nullfs/null_vfsops.c
Modified: head/sys/fs/nullfs/null_vfsops.c
==============================================================================
--- head/sys/fs/nullfs/null_vfsops.c Fri Feb 8 08:15:29 2019
(r343897)
+++ head/sys/fs/nullfs/null_vfsops.c Fri Feb 8 08:17:31 2019
(r343898)
@@ -145,10 +145,13 @@ nullfs_mount(struct mount *mp)
/*
* Check multi null mount to avoid `lock against myself' panic.
*/
- if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
- NULLFSDEBUG("nullfs_mount: multi null mount?\n");
- vput(lowerrootvp);
- return (EDEADLK);
+ if (mp->mnt_vnodecovered->v_op == &null_vnodeops) {
+ nn = VTONULL(mp->mnt_vnodecovered);
+ if (nn == NULL || lowerrootvp == nn->null_lowervp) {
+ NULLFSDEBUG("nullfs_mount: multi null mount?\n");
+ vput(lowerrootvp);
+ return (EDEADLK);
+ }
}
xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
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