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Before using VTONULL(), check that the covered vnode belongs to nullfs.

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Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2019-02-08 08:17:31 +00:00
parent 930cc2dbef
commit 25728e8411
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=343898
1 changed files with 7 additions and 4 deletions
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11
sys/fs/nullfs/null_vfsops.c
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@ -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),